Antibodies against human parathyroid hormone related protein

ABSTRACT

Disclosed are an antibody against human para-thyroid-hormone-related protein, a DNA coding for the antibody, a recombinant vector containing the DNA, a transformant transformed with the recombinant vector, a method for preparation of the antibody, and uses of the antibody.

This is a division of application Ser. No. 09/269,332, filed on Mar. 25,1999 now U.S. Pat. No. 6,903,194, which is a National Stage applicationof PCT/JP97/03382, and which claims benefit of Japanese Application No.255196/1996, filed on Sep. 26, 1996, and Japanese Application No.214168/1997, filed on Jul. 24, 1997, all of which are incorporatedherein by reference.

TECHNICAL FIELD

The present invention relates to a human/mouse chimeric antibodycomprising a variable region (V region) of a mouse monoclonal antibodyagainst a parathyroid hormone related protein and a constant region (Cregion) of a human antibody, a humanized antibody in whichcomplementarity determining regions of the light chain (L chain) andheavy chain (H chain) V regions of a mouse monoclonal antibody against aparathyroid hormone related protein (PTHrP) are grafted to a humanantibody, the L and H chains of said antibody, as well as a polypeptidecomprising the V region constituting the L or H chain of said antibody.

The present invention also relates to a DNA comprising a base sequencecoding for the above mentioned antibody, particularly its V region, anda DNA coding for an L or H chain comprising the V region. Further, thepresent invention relates to a recombinant vector comprising said DNAand a host transformed with said vector.

Furthermore, the present invention relates to processes for preparingthe chimeric and humanized antibodies against a PTHrP. Still further,the present invention relates to a pharmaceutical composition, andhypercalcemia-suppressing or hypophosphatemia-improving agent comprisingthe antibody against a PTHrP as an effective ingredient.

BACKGROUND OF THE INVENTION

Hypercalcemia associated with malignant tumor is a serious complicatedsymptom found in 5 to 20% of the whole patients suffering from malignanttumor and is considered to be a terminal symptom of malignant tumorsince it certainly leads to death if it is left as it is. Control ofhypercalcemia may greatly affect the prognosis and QOL (quality of life)of a patient; therefore, it will clinically play a significant role.

Generally, hypercalcemia in patients suffering from malignant tumor isroughly classified between HHM (humoral hypercalcemia of malignancy)based on tumor-producing humoral bone resorption factors and LOH (localosteolytic hypercalcemia) based on local action of tumor transferred orinfiltrated to the bone. In HHM, it is believed that bone resorption orosteoclasis is promoted to increase the flow of calcium and produceshypercalcemia in cooperation with the reduced renal calcium-excretingability (S. Wada and N. Nagata, Internal Medicine, 69, 644-648).

Hypercalcemia is considered to exhibit its symptoms when theconcentration of calcium in the serum exceeds 12 mg/dl; as its symptoms,anorexia (inappetence), nausea and emesis (vomiting) arenon-specifically observed at the early stage in patients suffering frommalignant tumor. When hypercalcemia is worsened, the reduction ofwater-concentrating ability due to lesion of the renal distal tubulesleads to hyperuresis (polyuria) and anorexia and nausea will beaccompanied with dehydration due to insufficient uptake of water.

As humoral factors causing HHM among the hypercalcemia associated withmalignant tumor, Moseley, J. M. et al. found parathyroid hormone relatedprotein (hereinafter referred to as “PTHrP”) which are substances likeparathyroid hormone (PTH): Proc. Natl. Acad. Sci. USA (1987) 84,5048-5052.

Thereafter, a gene coding for PTHrP was isolated (Suva, L. J. et al.,Science (1987) 237, 893) and it was elucidated from its analysis thatthere are three kinds of human PTHrPs having 139, 141 and 173 aminoacids due to alternative splicing of the gene and that various fragmentsare present in the blood due to restricted degradation of PTHrP (1-139)having the whole structure: Baba, H., Clinical Calcium (1995) 5,229-223. In PTHrP, 8 amino acids of the N-terminal 13 amino acids areidentical with those in PTH and it is deduced that the amino acid siteat position 14 to position 34 has a steric structure similar to PTH aswell; thus, PTHrP and PTH bind to a common PTH/PTHrP receptor at leastin the N-terminal region: Jueppner, H. et al., Science (1991) 254,1024-1026; Abou-Samra, A-B. et al., Proc. Natl. Acad. Sci. USA (1992)89, 2732-2736.

PTHrP is reported to be produced in a variety of tumoral tissues and ithas been elucidated that not only in tumors, PTHrP is also produced invarious normal tissues of from fetuses to adults, including skin,central nervous system, uterus, placenta, lactating mammary gland,thyroid gland, parathyroid gland, adrenal gland, liver, kidney andurinary bladder: Burtis, W. J., Clin. Chem. (1992) 38, 2171-2183;Stewart, A. F. & Broadus, A. E., J. Clin. Endocrinol. (1991) 71,1410-1414. Further, PTHrP is considered to play an important role in themetabolic regulation of calcium which is maintained at a higher level inthe fetal to newborn period than in the mother.

PTH/PTHrP receptors are known to be present mainly in the bone andkidney (C. Shigeno, Clinical Calcium (1995) 5, 355-359) and to activateplural intracellular signal transmission systems by binding of PTHrP tothe receptors. One of them is adenylate cyclase and the other isphospholipase C. Activation of adenylate cyclase increases theconcentration of intracellular cAMP to activate protein kinase A.Phospholipase C decomposes phosphatidylinositol 4,5-bisphosphonate toproduce inositol 1,4,5-triphosphonate and diacylglycerol. G-protein isinvolved in these signal transmission systems: Coleman, D. T. et al.,Biochemical mechanisms of parathyroid hormone action. In: “Theparathyroids” (Bilezikian, J. P. et al.), Raven Press, New York (1994)page 239.

Through these signal transmission systems, PTHrP causes hypercalcemia,hypophosphatemia, decrease of renal phosphate-resorbing ability,increase of renal cAMP-excretion and the like which are observed in HHM.

Thus, it has been elucidated that PTHrP is closely related tohypercalcemia associated with malignant tumor. In the treatment ofhypercalcemia associated with malignant tumor, calcitonin, steroidagents, indomethacin, inorganic phosphate salts, bisphosphonates and thelike are used, as well as fluid replacement. However, these agents mayshow reduction of their effects upon consecutive use, some seriousside-effects, or slow expression of their pharmacological effects;accordingly, use of agents or drugs which have higher therapeuticeffects and less side-effects is highly expected.

On the other hand, as a new attempt to treat hypercalcemia associatedwith malignant tumor, Kukreja, S. C. et al. reported that when aneutralizing antiserum against PTHrP was administered to athymic mice inwhich human lung or larynx cancer cells had been transplanted togenerate hypercalcemia, the blood calcium concentration and urinary cAMPlevel were reduced: J. Clin. Invest. (1988) 82, 1798-1802. Kanji Sato etal. reported that when an antibody against PTHrP (1-34) was administeredto nude mice to which a PTHrP-producing human tumor was transplanted,the hypercalcemia was reduced and the viable time period of the mice wasgreatly prolonged: J. bone & Mine. Res. (1993) 8, 849-860. Further,Japanese Patent Application Laid Open Publication No. 4-228089 disclosesmouse/human chimeric antibodies against human PTHrP (1-34).

Mouse monoclonal antibodies are highly immunogenic (sometimes alsoreferred to as “antigenic”) in humans, which limits the medicaltherapeutic values of the mouse monoclonal antibodies in humans. Forinstance, a mouse antibody may be metabolized as a foreign matter whenadministered to a human; therefore, the half-life of the mouse antibodyis relatively short in humans and its expected effects are notsufficiently exhibited. Further, human anti-mouse antibodies (HAMA)raised against the administered mouse antibody may cause immuneresponses which are inconvenient and dangerous to patients, such asserum diseases and other allergic reactions. Accordingly, mousemonoclonal antibodies can not frequently be administered to humans.

In order to solve these problems, methods for reducing theimmunogenicity of non-human derived antibodies, for example,mouse-derived monoclonal antibodies have been developed. One of thesemethods is to make a chimeric antibody in which the variable region (Vregion) is derived from a mouse monoclonal antibody and the constantregion (C region) is derived from an appropriate human antibody.

Since the resulting chimeric antibody has the intact variable region ofthe original mouse antibody, it can be expected that the chimericantibody may bind to an antigen with the same specificity as theoriginal mouse antibody. Further, such a chimeric antibody has asubstantially reduced proportion of an amino acid sequence derived froma non-human animal; therefore, it is anticipated to have a lowerimmunogenicity as compared with the original mouse antibody. Althoughthe chimeric antibody binds to its antigen equivalently with theoriginal mouse monoclonal antibody while showing a lower immunogenicity,some immune responses to the mouse variable region may still be possiblygenerated: LoBuglio, A. F. et al., Proc. Natl. Acad. Sci. USA, 86,4220-4224, 1989.

A second method for reducing the immunogenicity of mouse antibodies isstill more complicated but expected to further greatly reduce thepotential immunogenicity of the mouse antibodies. In this method, onlythe complementarity determining regions (CDRs) of the variable region ofa mouse antibody are grafted to a human variable region to create a“reshaped” human variable region. If required, a partial amino acidsequence of a framework region (FR) supporting the CDRs in a variableregion of a mouse antibody may be grafted to a human variable region inorder to make the structure of CDRs in the reshaped human variableregion closer to that of the original mouse antibody.

Then, these humanized, reshaped human variable regions are combined withhuman constant regions. In the finally reshaped, humanized antibody, theportions derived from non-human amino acid sequences are only CDRs and avery small part of FR. The CDRs are composed of a hypervariable aminoacid sequence and these do not show any species-specific sequences.Therefore, a humanized antibody comprising mouse CDRs will no longerhave any stronger immunogenicity than a naturally occurring humanantibody containing human CDRs.

With respect to humanized antibodies, further reference should be madeto Riechmann, L. et al., Nature, 332, 323-327, 1988; Verhoeye, M. etal., Science, 239, 1534-1536, 1988; Kettleborough, C. A. et al., ProteinEngng., 4, 773-783, 1991; Maeda, H. et al., Human Antibodies andHybridoma, 2, 124-134, 1991; Gorman, S. D. et al., Proc. Natl. Acad.Sci. USA, 88, 4181-4185, 1991; Tempest, P. R. et al., Bio/Technology, 9,266-271, 1991; Co, M. S. et al., Proc. Natl. Acad. Sci. USA, 88,2869-2873, 1991; Carter, P. et al., Proc. Natl. Acad. Sci. USA, 89,4285-4289, 1992; Co, M. S. et al., J. Immunol., 148, 1149-1154 1992; andSato, K. et al., Cancer Res., 53, 851-856, 1993.

Although humanized antibodies are expected to be useful for therapeuticpurposes as previously mentioned, no humanized antibody against PTHrPhas been known nor suggested in the aforementioned references. Further,there is no standardized means generally applicable to any antibodies inthe process for preparing humanized antibodies; various means andmethods are necessary to make a humanized antibody exhibiting asufficient binding, neutralizing activity to a specific antigen: see,for example, Sato, K. et al., Cancer Res., 53, 851-856, 1993.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a human/mousechimeric antibody comprising a variable region (V region) of a mousemonoclonal antibody against PTHrP and a constant region (C region) of ahuman antibody, a humanized antibody in which complementaritydetermining regions of V regions of the light chain (L chain) and heavychain (H chain) of a mouse monoclonal antibody against PTHrP are graftedto a human antibody, the L and H chains of said antibody, as well as apolypeptide comprising the V region constituting the L or H chain ofsaid antibody.

It is another object of the present invention to provide a DNAcomprising a base sequence coding for the above mentioned antibody,particularly its V region, and a DNA coding for an L or H chaincomprising a polypeptide comprising the V region. Still another objectof the present invention is to provide a recombinant vector comprisingsaid DNA and a host transformed with said vector. Further, an object ofthe present invention is to provide processes for preparing the chimericand humanized antibodies against PTHrP. It is a still another object ofthe present invention to provide an antibody against PTHrP having a highneutralizing activity. A still further object of the present inventionis to provide a pharmaceutical composition, andhypercalcemia-suppressing, hypophosphatemia-improving oralkalosis-improving agent comprising the antibody or humanized antibodyagainst PTHrP as an effective ingredient.

As a result of the energetic study with a view to the above mentionedobjects, the present inventors have successfully obtained an antibody inwhich the immunogenicity of mouse monoclonal antibodies against PTHrP isreduced in humans; thus, the present invention has been accomplished.

The present invention is directed to a chimeric L chain comprising an Lchain C region of a human antibody and an L chain V region of a mousemonoclonal antibody against PTHrP. The L chain V region includes onecomprising an amino acid sequence as shown in SEQ ID NO:45 and the Lchain C region includes a Cλ region.

The present invention is also directed to a chimeric H chain comprisingan H chain C region of a human antibody and an H chain V region of amouse monoclonal antibody against PTHrP. The H chain V region includesone comprising an amino acid sequence as shown in SEQ ID NO:46 and the Cregion includes a Cγ1 region.

Further, the present invention is directed to a chimeric monoclonalantibody against PTHrP comprising said chimeric L chain and saidchimeric H chain.

Still further, the present invention includes a polypeptide comprisingan L chain V region of a humanized antibody comprising framework regions1 to 4 of an L chain V region of a human antibody and complementaritydetermining regions 1 to 3 of an L chain V region of a mouse monoclonalantibody against PTHrP. The complementarity determining regions 1 to 3include those comprising amino acid sequences as shown in SEQ IDNOs:59-61, respectively; the framework regions 1 to 3 include thosederived from the framework regions 1 to 3 of human antibody HSU03868,respectively, and the framework region 4 includes one derived from theframework region 4 of human antibody S25755; or the framework regions 1to 3 include those substantially identical with the framework regions 1to 3 of human antibody HSU03868, respectively, and the framework region4 includes one substantially identical with the framework region 4 ofhuman antibody S25755.

The term “substantially identical” as used herein means that theframework regions of the human antibody used in a humanized antibody mayhave a deletion, replacement and/or addition of amino acid(s) requiredto form the complementarity determining regions of a mouse monoclonalantibody such that the humanized antibody should have an activityequivalent to that of the mouse monoclonal antibody.

Thus, the present invention is concerned with a polypeptide comprisingan L chain V region of a humanized antibody wherein in the frameworkregions the 36th and 49th amino acids in accordance with Kabat'sprescription (Kabat, E. A. et al., US Dept. Health and Human Services,US Government Printing Offices, 1991) are tyrosine and aspartic acid;respectively.

The present invention is also directed to a polypeptide comprising an Lchain V region of a humanized antibody comprising an amino acid sequenceas shown in any of SEQ ID NOs:48-51.

Further, the present invention is directed to a polypeptide comprisingan L chain V region of a humanized antibody wherein the 45th and 87thamino acids in accordance with Kabat's prescription in the frameworkregions are lysine and isoleucine, respectively.

Still further, the present invention is directed to a polypeptidecomprising an L chain V region of a humanized antibody comprising anamino acid sequence as shown in any of SEQ ID NOs: 52-55.

The present invention is further concerned with a polypeptide comprisingan H chain V region of a humanized antibody comprising framework regions1 to 4 of an H chain V region of a human antibody and complementaritydetermining regions 1 to 3 of an H chain V region of a mouse monoclonalantibody against a human PTHrP. The complementarity determining regions1 to 3 include those comprising amino acid sequences as shown in SEQ IDNOs:62-64, respectively, the framework regions 1 to 4 include thosederived from framework regions 1 to 4 of a human antibody belonging tohuman subgroup III (Human Subgroup III (HSG III), Kabat, E. A. et al.,US Dept. Health and Human Services, US Government Printing Offices,1991), more particularly those derived from the framework regions 1 to 4of human antibody S31679, respectively, or those substantially identicalwith the framework regions 1 to 4 of human antibody S31679,respectively.

Also, the present invention is concerned with a polypeptide comprisingan H chain V region of a humanized antibody comprising the amino acidsequence as shown in SEQ ID NO:56.

The present invention is also concerned with an L chain of a humanizedantibody against a human PTHrP comprising a polypeptide comprising an Lchain V region of said humanized antibody and a polypeptide comprisingan L chain C region of a human antibody. The C region includes a Cλregion, the framework regions 1 to 3 include those substantiallyidentical with the framework regions 1 to 3 of human antibody HSU03868,respectively, the framework region 4 includes one substantiallyidentical with the framework region 4 of human antibody S25755, and theamino acid sequences of the complementarity determining regions 1 to 3include those represented by SEQ ID NOs:59-61, respectively.

Further, the present invention is also concerned with an H chain of ahumanized antibody against a human PTHrP comprising polypeptidescomprising an H chain C region and H chain V region of said humanantibody. The C region includes a Cγ1 region, the framework regions 1 to4 include those derived from the framework regions 1 to 4 derived from ahuman antibody belonging to HSGIII, and the complementarity determiningregions 1 to 3 include those comprising the amino acid sequences asshown in SEQ ID NOs:62-64, respectively.

Still further, the present invention is also concerned with ananti-PTHrP antibody with a weak antigenicity and a high neutralizingactivity. The PTHrP antibody includes a human antibody, a humanizedantibody, a chimeric antibody and a primatized antibody, which may beutilized in the treatment of human diseases. The antibody has a lowdissociation constant. Further, the antibody of the present inventionhas a high neutralizing activity due to its low dissociation constantand, therefore, can be utilized for the treatment of human diseases.

The antibody of the present invention has a dissociation constant of1.86×10⁻⁷ [M] or less, a dissociation rate constant of 1.22×10⁻¹ [l/Sec]or less, and an association rate constant of 6.55×10⁴ [l/M.Sec] or more.These constants may be measured by Scatchard analysis using RI labeledligands or Surface plasmon resonance sensor.

The present invention is further directed to a DNA comprising a basesequence coding for an L chain V region or H chain V region of a mousemonoclonal antibody against a human PTHrP. The L chain V region and Hchain V region include those comprising the amino acid sequence as shownin SEQ ID NOs:45-46, respectively, the DNA comprising a base sequencecoding for the L chain V region includes, for example, one representedby SEQ ID NO:65, and the DNA comprising a base sequence coding for the Hchain V region includes one represented by SEQ ID NO:57.

Further, the present invention is also directed to a DNA coding for saidchimeric L or H chain. The DNA coding for said L chain includes, forexample, one comprising the base sequence as shown in SEQ ID NO:65 andthe DNA coding for said H chain includes one comprising the basesequence as shown in SEQ ID NO:57.

Still further, the present invention is also directed to a DNAcomprising a base sequence coding for an L chain V region or H chain Vregion of said humanized antibody. The DNA comprising a base sequencecoding for the L chain V region includes one comprising the basesequence as shown in any of SEQ ID NOs:66-74 and the DNA comprising abase sequence coding for the H chain V region includes one representedby SEQ ID NO:58.

The present invention also relates to a DNA for an L chain V region of ahumanized antibody comprising a base sequence coding for the amino acidsequence as shown in any of SEQ ID NOs:47-55. Said DNA includes onecomprising the base sequence as shown in any of SEQ ID NOs:66-74.

Still further, the present invention relates to a DNA for an H chain Vregion of a humanized antibody coding for the amino acid sequence asshown in SEQ ID NO:56. Said DNA includes one comprising the basesequence as shown in SEQ ID NO:58.

The present invention further relates to a recombinant vector comprisingany of said DNAs.

The present invention still further relates to a transformanttransformed with said recombinant vector.

Also, the present invention relates to a process for preparing achimeric or humanized antibody against a human parathyroid hormonerelated protein comprising cultivating said transformant and collectinga chimeric or humanized antibody against a human parathyroid hormonerelated protein from the resulting culture.

Still further, the present invention also relates to a pharmaceuticalcomposition, or hypercalcemia-suppressing or hypophosphatemia-improvingagent comprising said antibody as an effective ingredient. The calcemiais caused by malignant tumor and the hypophosphatemia is often observedin patients suffering from hypercalcemia associated with malignanttumor. Thus, the antibody of the present invention can be used in thetreatment of the malignant tumor or in the improvement of hypercalcemiaor hypophosphatemia symptoms. The malignant tumor may include, but notlimited to, at least one selected from the group consisting of pancreas,lung, pharynx, larynx, tongue, gingiva, esophagus, stomach, biliaryduct, breast, kidney, urinary bladder, uterus and prostate cancers, andmalignant lymphoma. The hypercalcemia-suppressing agent of the presentinvention can be applicable to any malignant tumor which may causehypercalcemia.

The present invention will be described in detail hereinbelow.

1. Production of Mouse Monoclonal Antibodies Against Human PTHrP

Mouse monoclonal antibodies against PTHrP may be prepared by preparinghybridomas through cell fusion between myeloma cells andantibody-producing cells derived from animals immunized with the antigenand selecting clones producing antibodies specifically inhibiting thePTHrP activity from the resulting hybridomas.

(1) Preparation of Antigens

PTHrP used for the immunization of animals includes peptides having thewhole or part of the amino acid sequence of PTHrP prepared byrecombinant DNA technology or chemical synthesis, and PTHrP derived fromsupernatants of cancer cells causing hypercalcemia. For example, apeptide [PTHrP(1-34) ] comprising the 1st to 34th amino acids of theknown PTHrP (Kemp, B. E. et al., science (1987) 238, 1568-1570) may beused as the antigen. The human PTHrP(1-34) has an amino acid sequence asshown in SEQ ID NO:75.

The resultant PTHrP is attached to a carrier protein such asthyroglobulin followed by addition of an adjuvant. Any adjuvant may bemixed, including Freund's complete and incomplete adjuvants.

(2) Immunization and Collection of Antibody Producing Cells

The above resultant antigen is administered to a mammal, such as mouse,rat, horse, monkey, rabbit, goat or sheep. Immunization may be carriedout by any known methods, including intravenous, subcutaneous andintraperitoneal injections. Intervals of injections for immunization arenot particularly limited and may be a few days to a few weeks,preferably 4 to 21 days.

Two or three days after final immunization, antibody producing cells arecollected. The antibody producing cells include spleen, lymph node andperipheral blood cells; generally, spleen cells are utilized. The singledose amount of antigen used for immunization is 100 μg per mouse.

(3) Determination of Antibody Titers

In order to determine the immune response levels of immunized animalsand select hybrodomas of interest from the cells subjected to cellfusion treatment, the antibody titer in the blood of the immunizedanimal or the antibody titer in the supernatant of the antibodyproducing cells is measured.

Methods for detecting the antibodies are known, including EIA (enzymeimmunoassay), RIA (radio immunoassay), and ELISA (enzyme linkedimmunosorbent assay).

(4) Cell Fusion

Myeloma cells used to be fused with antibody producing cells includecell lines which are derived from various animals such as mouse, rat andhuman, and generally available for those skilled in the art. Suitablecell lines used are those having a drug resistance, incapable ofsurviving in a selective medium such as HAT medium in the unfused state,and capable of surviving therein only in the fused state. Generally usedare 8-azaguanine resistant cell lines, which lackhypoxanthine-guanine-phosphoribosyltransferase and can not grow in ahypoxanthine-aminopterin-thymidine (HAT)-medium.

Suitable myeloma cells to be used include various known cell lines, suchas P3 (P3x63Ag8.653) (J. Immunol. (1979) 123:1548-1550); P3x63Ag8U.1(Current Topics in Microbiology and Immunology (1978) 81:1-7); NS-1(Kohler, G and Milstein, C., Eur. J. Immunol. (1976) 6:511-519); MPC-11(Margulies, D. H. et al., Cell (1976) 8:405-415) SP2/0 (Shulman, M. etal., Nature (1978) 276:269-270); FO (de St. Groth, S. F. et al., J.Immunol. Methods (1980) 35:1-21); S194 (Trowbridge, I. S., J. Exp. Med.(1978) 148:313-323); and R210 (Galfre, G. et al., Nature (1979)277:131-133).

Antibody producing cells may be obtained from spleen cells, lymph nodecells, or the like. That is, the spleen, lymph node or the like isextracted or removed from any of the aforementioned animals and thetissue is crushed. The resulting crushed materials are suspended in amedium or buffer, such as PBS, DMEM or RPMI1640, filtered throughstainless mesh or the like and centrifuged to prepare the desiredantibody producing cells.

Then, said myeloma cells and antibody producing cells are subjected tocell fusion.

Cell fusion may be carried out by bringing the myeloma andantibody-producing cells into contact with each other at a ratio of 1:1to 1:10 in a medium for the culture of animal cells, such as MEM, DMEMor RPME-1640, in the presence of a fusion accelerator at 30 to 37° C.for 1 to 15 minutes. To accelerate the cell fusion, any fusionaccelerator or virus can be used, such as polyethylene glycol with anaverage molecular weight of 1,000 to 6,000, polyvinyl alcohol or Sendaivirus. The fusion of the antibody producing and myeloma cells may alsobe performed in a commercially available cell fusion apparatus utilizingan electric stimulation such as electroporation.

(5) Selection and Cloning of Hybridomas

Hybridomas of interest are selected from the cells after the cellfusion, for example, by a method utilizing selective growth of cells inselective media.

That is, a cell suspension is diluted with a suitable medium andinoculated on a microtiter plate. A selective medium such as HAT mediumis added to each well and incubated while properly replacing theselective medium with a fresh one.

Thus, the growing cells are collected as hybridomas.

These hybridomas are then screened by the limiting dilution,fluorescence-activated cell sorter or other method. Finally, hybridomasproducing a monoclonal antibody are obtained.

(6) Collection of Monoclonal Antibodies

Methods for collecting monoclonal antibodies from the obtainedhybridomas include conventional cell culture and ascites formationmethods.

In the cell culture method, the hybridomas are cultivated in a mediumfor the culture of animal cells, such as RPMI-1640 medium containing 10to 20% fetal bovine serum, MEM medium or serum-free medium, underconventional conditions (e.g., 37° C., 5% CO₂) for 2 to 14 days and theantibodies are collected from the supernatant.

In the formation of ascites, the hybridomas are inoculatedintraperitoneally to the same species of mammal as the source of themyeloma cells so that the hybridomas grow abundantly. After 1 to 4weeks, the ascites or sera are collected.

When the antibodies are necessary to be purified in these methods, knownmethods such as the ammonium sulfate precipitation, ion exchangechromatography and affinity chromatography may optionally be selected orcombined.

2. Construction of Chimeric Antibodies

(1) Cloning of DNA Comprising Base Sequence Coding for V Region of MouseMonoclonal Antibody Against Human PTHrP

(i) Preparation of mRNA

To clone DNA comprising a base sequence coding for V region of mousemonoclonal antibody against human PTHrP, the collected hybridomas aretreated in a conventional manner, for example,guanidine-ultracentrifugation (Chirgwin, J. M. et al., Biochemistry(1979) 18, 5294-5299), or AGPC method (Chomczynski, P et al., AnalyticalBiochemistry (1987) 162, 156-159), to prepare the total RNA, from whichmRNA is prepared by e.g. Oligo(dT)-cellulose span column attached tomRNA Purification Kit (Pharmacia). Quick-Prep mRNA Purification Kit(Pharmacia AB) can also be used to prepare mRNA without need ofextraction of the total RNA.

(ii) Preparation and Amplification of cDNA

From the mRNA obtained in (i) above, each cDNA in the V regions of L andH chains is synthesized with the use of a reverse transcriptase. In thesynthesis of cDNA, Oligo-dT primer or an other appropriate primer whichhybridizes to L or H chain C region, for example, MHC2 primer having thebase sequence as shown in SEQ ID NO:1, may be used.

In the cDNA synthesis, said mRNA and primer are mixed and the reactionis effected in'the presence of a reverse transcriptase at e.g. 52° C.for 30 minutes.

Amplification of cDNA of both L and. H chains can be performed by PCR(polymerase chain reaction) based on 5′-RACE method (Frohman, M. A. etal., Proc. Natl. Acad. Sci. USA, 85, 8998-9002, 1988; Belyavsky, A. etal., Nucleic Acids Res., 17, 2919-2932, 1989) using 5′-Ampli FINDER RACEkit (CLONTECH Inc.). Thus, Ampli FINDER Anchor (SEQ ID NO:42) is linkedto 5′ end of the cDNA synthesized above and PCR is effected for DNAscomprising base sequences coding for L and H chain V regions.(Hereinafter, the DNA comprising a base sequence coding for L chain Vregion is sometimes referred to simply as “DNA for L chain V region” or“DNA coding for L chain V region”. This also applies to H chain Vregion, C region etc. similarly.)

The primer for amplifying DNA for L chain V region which may be usedincludes, for example, Anchor primer (SEQ ID NO:2) and primers designedfrom conserved sequences in Lλ chain constant region (C-λ region) ofmouse antibodies such as MLC primer having the base sequence as shown inSEQ ID NO:4. The primer for amplifying DNA for H chain V region whichmay be used includes, for example, Anchor primer (SEQ ID NO:2) andMHC-G1 primer (SEQ ID NO:3) (S. T. Jones, et al., Biotechnology, 9, 88,1991).

(iii) Purification of DNA and Determination of Base Sequence

The PCR products are subjected to agarose gel electrophoresis accordingto conventional procedures to excise DNA fragments of interest, whichare then recovered, purified and ligated to a vector DNA.

Purification of DNA may be carried out using commercially available kitssuch as GENECLEAN II; BIO101. Vector DNA for carrying the DNA fragmentswhich may be used herein is known, for example, pUC19 or Bluescript.

Said DNA and vector DNA are ligated using a known ligation kit (TakaraShuzo) to yield a recombinant vector. The resultant recombinant vectoris introduced into e.g. Escherichia coli JM109 and ampicillin resistantcolonies are selected; thus, a vector DNA is prepared in a known method:J. Sambrook, et al., “Molecular Cloning”, Cold Spring Harbor LaboratoryPress, 1989. After the vector DNA is digested with restrictionenzyme(s), the base sequence of a desired DNA is determined by a knownmethod such as dideoxy method: J. Sambrook, et al., “MolecularCloning”,Cold Spring Harbor Laboratory Press, 1989. In the present invention, anautomated base sequence determining apparatus (DNA Sequencer 373A; ABIInc.) may be used.

(iv) Complementarity Determining Region

H and L chain V regions form an antigen binding site and their wholestructures have some similarity to each other. That is, four frameworkregion (FR) portions are linked through three hypervariable regions, orcomplementarity determining region (CDR). The amino acid sequence in theFR is relatively well conserved while variability of the amino acidsequence in the CDR region is very high: Kabat, E. A. et al, “Sequenceof Proteins of Immunological Interest” US Dept. Health and HumanServices, 1983.

Many portions of the four FRs have β sheet structure and, as a result,three CDRs form a loop. The CDR may sometimes form a part of the β sheetstructure. Therefore, three CDRs are sterically held at very nearpositions to each other by FRs, which form an antigen binding sitetogether with the three CDRs in the paired regions.

In view of such facts, CDR regions can be found by comparison betweenthe amino acid sequence in the variable region of a mouse monoclonalantibody against human PTHrP and the database of amino acid sequencesfor antibodies prepared by Kabat et al. (“Sequence of Proteins ofImmunological Interest” US Dept. Health and Human Services, 1983) toinvestigate the homology therebetween.

(2) Construction of Expression Vector of Chimeric Antibody

Once DNA fragments coding for L and H chain V regions of mousemonoclonal antibody (hereinafter L or H chain of an antibody maysometimes be referred to as “mouse L chain” etc. for mouse antibodiesand “human H chain” etc. for human antibodies) are cloned, the DNAscoding for mouse V regions and DNAs coding for human antibody constantregions are ligated and expressed to yield chimeric anti-human PTHrPantibodies.

A standard method for preparing chimeric antibodies involves ligating amouse leader sequence and V region sequence present in a cloned cDNA toa sequence coding for a human antibody C region already present in anexpression vector of a mammalian cell. Alternatively, a mouse leadersequence and V region sequence present in a cloned cDNA are ligated to asequence coding for a human antibody C region followed by ligation to amammalian cell expression vector.

The polypeptide comprising human antibody C region can be any of H or Lchain C regions of human antibodies, including, for example, Cγ1, Cγ2,Cγ3 or Cγ4 for human H chains or Cλ or Cκ for L chains.

To prepare a chimeric antibody, two expression vectors are firstconstructed; that is, an expression vector containing DNAs coding formouse L chain V region and human L chain C region under the control ofan expression control region such as an enhancer/promoter system, and anexpression vector containing DNAs coding for mouse H chain V region andhuman H chain C region under the control of an expression control regionsuch as an enhancer/promoter system, are constructed. Then, host cellssuch as mammalian cells are cotransformed with these expression vectorsand the transformed cells are cultivated in vitro or in vivo to producea chimeric antibody: see, for example, WO91/16928.

Alternatively, the mouse leader sequence present in the cloned cDNA andDNAs coding for mouse L chain V region and human L chain C region aswell as the mouse leader sequence and DNAs coding for mouse H chain Vregion and human H chain C region are introduced into a singleexpression vector (see, for example, WO94/11523) and said vector is usedto transform a host cell; then, the transformed host is cultivated invivo or in vitro to produce a desired chimeric antibody.

(i) Production of Chimeric Antibody H Chain

The vector for the expression of H chain of a chimeric antibody can beobtained by introducing cDNA comprising a base sequence coding for mouseH chain V region (hereinafter referred to also as “cDNA for H chain Vregion”) into a suitable expression vector containing the genomic DNAcomprising a base sequence coding for H chain C region of human antibody(hereinafter referred to also as “genomic DNA for H chain C region”) orcDNA coding for said region (hereinafter referred to also as “cDNA for Hchain C region”). The H chain C region includes, for example, Cγ1, Cγ2,Cγ3 or Cγ4 regions.

(i-a) Construction of Chimeric H Chain Expression Vector ContainingGenomic DNA Coding for H Chain C Region

The expression vectors having the genomic DNA coding for H chain Cregion, in particular, those coding for Cγ1 region, include, forexample, HEF-PMh-gγ1 (WO92/19759) and DHFR-ΔE-RVh-PM1-f (WO92/19759).

When cDNA coding for mouse H chain V region is inserted into theseexpression vectors, an appropriate base sequence can be introduced intosaid cDNA through PCR method. For instance, PCR may be effected using aPCR primer which is designed such that said cDNA has a recognitionsequence for a suitable restriction enzyme at its 5′-end and Kozakconsensus sequence immediately before the initiation codon thereof so asto improve the transcription efficiency, as well as a PCR primer whichis designed such that said cDNA has a recognition sequence for asuitable restriction enzyme at its 3′-end and a splice donor-site forproperly splicing the primary transcription products of the genomic DNAto give a mRNA, to introduce these appropriate base sequences into theexpression vector.

After the thus constructed cDNA coding for mouse H chain V region istreated with a siutable restriction enzyme(s), it is inserted into saidexpression vector to construct a chimeric H chain expression vectorcontaining the genome DNA coding for H chain C region (Cγ1 region).

(i-b) Construction of Chimeric H Chain Expression Vector Containing cDNAComprising Base Sequence Coding for H Chain

The expression vectors having the cDNA coding for H chain C region, suchas Cγ1 region, may be constructed in the following manner: mRNA isprepared from CHO cells into which an expression vectorDHFR-ΔE-RVh-PM1-f (see WO92/19759) comprising DNA coding for H chain Vregion of a humanized PM1 antibody and genomic DNA of H chain C regionCγ1 of a human antibody (N. Takahashi, et al., Cell, 29, 671-679 (1982))and an expression vector RV1-PM1a (see WO92/19759) comprising genomicDNA coding for L chain V region of the humanized PM1 antibody andgenomic DNA of Lκ chain C region of a human antibody have beenintroduced, and cDNA coding for the H chain V region of the humanizedPM1 antibody and cDNA coding for the H chain C region (Cγ1) of the humanantibody are cloned by RT-PCR method and ligated to an animal cellexpression vector which has been treated with a suitable restrictionenzyme(s), to construct a desired expression vector.

When cDNA coding for mouse H chain V region is directly ligated to cDNAcoding for H chain C region Cγ1 of a human antibody, appropriate basesequences can be introduced into a fragment comprising cDNA coding for Hchain V region through PCR method. For instance, PCR may be effectedusing a PCR primer which is designed such that said cDNA has arecognition sequence for a suitable restriction enzyme at its 5′-end andKozak consensus sequence immediately before the initiation codon thereofso as to improve the transcription efficiency, as well as a PCR primerwhich is designed such that said cDNA has a recognition sequence for asuitable restriction enzyme at its 3′-end for directly ligating to the Hchain C region Cγ1, to introduce these appropriate base sequences intosaid cDNA.

The thus constructed cDNA coding for mouse H chain V region is treatedwith a siutable restriction enzyme(s), ligated to cDNA coding for said Hchain C region Cγ1, and inserted into an expression vector such as pCOS1or pCHO1 to construct an expression vector containing the cDNA codingfor a chimeric H chain.

(ii) Production of Chimeric Antibody L Chain

The vector for the expression of L chain of a chimeric antibody can beobtained by ligating a cDNA coding for mouse L chain V region and agenomic DNA or cDNA coding for L chain C region of a human antibody andintroducing into a suitable expression vector. The L chain C regionincludes, for example, κ chain and λ chain.

(ii-a) Construction of Expression Vector Containing cDNA Coding forChimeric Lλ Chain

When an expression vector containing cDNA coding for mouse L chain Vregion is constructed, appropriate base sequences can be introduced intosaid expression vector through PCR method. For instance, PCR may beeffected using a PCR primer which is designed such that said cDNA has arecognition sequence for a suitable restriction enzyme at its 5′-end andKozak consensus sequence for improving the transcription efficiency, aswell as a PCR primer which is designed such that said cDNA has arecognition sequence for a suitable restriction enzyme at its 3′-end, tointroduce these appropriate base sequences into said cDNA.

The whole base sequence of cDNA coding for human Lλ chain C region maybe synthesized by a DNA synthesizer and constructed through PCR method.The human Lλ chain C region is known to have at least 4 differentisotypes and each isotype can be used to construct an expression vector.For example, based on a search for the homology with Lλ chain C regionsof cloned mouse monoclonal antibodies, an isotype Mcg+Ke+Oz− of thefragment of human Lλ chain C region (accession No. X57819) (P. Dariavachet al., Proc. Natl. Acad. Sci. USA, 84, 9074-9078, 1987) can be selectedand used to construct an expression vector. To construct cDNA for theknown human Lλ chain C region such as Mcg+Ke+Oz−, for example, thefollowing four primers as shown in SEQ ID NOs:11-14 are designed: Theprimers MBC1HGP1 (SEQ ID NO:11) and MBC1HGP3 (SEQ ID NO:13) have senseDNA sequences and the primers MBC1HGP2 (SEQ ID NO:12) and MBC1HGP4 (SEQID NO:14) have antisense DNA sequences wherein each primer has a 20 to23 bp complementary sequence at either end thereof.

MBC1HGPS (SEQ ID NO:15) and MBC1HGPR (SEQ ID NO:16) are called externalprimers, have sequences homologous with MBC1HGP1 and MBC1HGP4,respectively, and have each a recognition sequence for a suitablerestriction enzyme. Through PCR method, the four primers are assembledto synthesize full length cDNA and the external primers are added toamplify the cDNA.

The assembly through PCR method means that MBC1HGP1 and MBC1HGP2 orMBC1HGP3 and MBC1HGP4 are annealed through their complementary sequencesto synthesize MBC1HGP1-MBC1HGP2 fragment and MBC1HGP3-MBC1HGP4 fragmentand each fragment is again annealed through their complementarysequences to synthesize a cDNA coding for the full length human Lλ chainC region.

The thus constructed cDNA coding for human Lλ chain C region and theabove constructed cDNA coding for mouse L chain V region can be ligatedbetween suitable restriction enzyme sites and inserted into anexpression vector such as pCOS1 or pCHO1 to construct an expressionvector containing cDNA coding for a Lλ chain of a chimeric antibody.

(ii-b) Construction of Expression Vector Containing cDNA Coding forChimeric Lκ Chain

When an expression vector containing cDNA coding for mouse L chain Vregion is constructed, appropriate base sequences can be introduced intosaid cDNA through PCR method. For instance, PCR may be effected using aPCR primer which is designed such that said cDNA has a recognitionsequence for a suitable restriction enzyme at its 5′-end and Kozakconsensus sequence for improving the transcription efficiency, and a PCRprimer which is designed such that said cDNA has a recognition sequencefor a suitable restriction enzyme at its 3′-end, to introduce theseappropriate base sequences into said cDNA.

The DNA coding for human Lκ chain C region to be ligated to the DNAcoding for mouse L chain V region can be constructed from, for example,HEF-PM1k-gk containing the genomic DNA (see WO92/19759)

Recognition sequences for suitable restriction enzymes can beintroduced, through PCR method, into 5′- and 3′-ends of DNA coding forLκ chain C region, and the DNA coding for mouse L chain V region asconstructed above and the DNA coding for Lκ chain C region can beligated to each other and inserted into an expression vector such aspCOS1 or pCHO1 to construct an expression vector containing cDNA codingfor Lκ chain of a chimeric antibody.

3. Production of Humanized Antibodies

(1) Search for Homology with Human Antibodies

In order to make a humanized antibody in which CDR of a mouse monoclonalantibody is grafted to a human antibody, it is desirable that thereexists a high homology between FR of the mouse monoclonal antibody andFR of the human antibody. Accordingly, a comparison is made between Vregions of H and L chains of mouse anti-human PTHrP monoclonal antibodyand the V regions of all the known antibodies whose structures have beenelucidated with the use of Protein Data Bank. Further, they aresimultaneously compared with the human antibody subgroups (HSG: Humansubgroup) classified by Kabat et al. based on the length of antibody FR,the homology of amino acids, and the like: Kabat, E. A. et al, US Dep.Health and Human Services, US Government Printing Offices, 1991.

Human H chain V regions may be classified into HSG I to III according tothe HSG classification by Kabat et al. and mouse anti-human PTHrPmonoclonal antibody H chain V regions have a homology of 82.7% with theconsensus sequence of HSG III. On the other hand, human Lλ chain Vregions may be classified into HSG I to VI according to the HSGclassification by Kabat et al. and mouse anti-human PTHrP monoclonalantibody Lλ chain V regions do not have a high homology with theconsensus sequences of human Lλ chain V regions belonging to anysubgroups.

When mouse anti-human PTHrP monoclonal antibody is to be humanized,therefore, it is desirable to use human H chain V region which belongsto HSG III and has the highest homology, or human H chain V regionhaving a FR structure with a corresponding canonical structure (ChothiaC, et al., J. Mol. Biol., 196, 901-917, 1987), as the human H chain Vregion, to construct a humanized antibody. Further, since there is noconsensus sequence with a high homology in subgroups of human Lλ chain Vregions, it is desirable to use human antibody Lλ chain V region with ahighest homology registered in Protein Data Bank upon construction of ahumanized antibody.

(2) Design of DNA Coding for Humanized Antibody V Region

The first step for designing DNA coding for a humanized antibody Vregion is to select a human antibody V region as a basis for thedesigning.

In the present invention, FR of a human antibody V region having ahomology of higher than 80% with FR of a mouse antibody V region can beused in the humanized antibody. The FR of H chain V region as a fragmentof a substantially identical FR may include FR derived from thosebelonging to the subgroup III, such as S31679: NBRF-PDB, Cuisinier A. M.et al., Eur. J. Immunol., 23, 110-118, 1993. Further, the FR of L chainV region as a fragment of a substantially identical FR may include, forexample, FR1, FR2 and FR3 derived from human antibody HSU03868(GEN-BANK, Deftos M. et al., Scand. J. Immunol., 39, 95-103, 1994) andFR4 derived from human antibody S25755 (NBRF-PDB).

The human antibody S31679 was cloned from cDNA library of human fetallivers while the human antibody HSU03868 was cloned as a novel gene forhuman Lλ chain V region.

(3) Preparation of Polypeptides Comprising Humanized Antibody V Region

In the humanized antibody of the present invention, the C region and theframework (FR) regions of the V region of said antibody are originatedfrom human and the complementarity determining regions (CDR) of the Vregion are originated from mouse (FIG. 1). A polypeptide comprising theV region of the humanized antibody according to the present inventioncan be made in the manner called CDR-grafting by PCR method so long as aDNA fragment of a human antibody would be available as a template. The“CDR-grafting” refers to a method wherein a DNA fragment coding for amouse-derived CDR is made and replaced for the CDR of a human antibodyas a template.

If a DNA fragment of a human antibody to be used as a template is notavailable, a base sequence registered in a database may be synthesizedin a DNA synthesizer and a DNA for a V region of a humanized antibodycan be made by the PCR method. Further, when only an amino acid sequenceis registered in the database, the whole base sequence may be deducedfrom the amino acid sequence on the basis of knowledge on the codonusage in antibodies as reported by Kabat, E. A. et al. in US Dep. Healthand Human Services, US Government Printing Offices, 1991. This basesequence is synthesized in a DNA synthesizer and a DNA of a humanizedantibody V region can be prepared by PCR method and introduced into asuitable host followed by expression thereof to produce the desiredpolypeptide.

Now, general procedures of CDR-grafting by PCR method are describedbelow when a DNA fragment of a human antibody as a template isavailable.

(i) CDR-Grafting

Now suppose DNA encoding V region comprises DNAs coding for FR1, CDR1,FR2, CDR2, FR3, CDR3 and FR4 which are linked to each other in thisorder, as shown in FIG. 2.

First, mouse derived DNA fragments corresponding to respective CDRs aresynthesized. CDRs 1 to 3 are synthesized on the basis of the basesequences of the previously cloned mouse H and L chain V regions.Grafting primers B and E are synthesized such that the primer B shouldhave a sequence hybridizing to the mouse CDR1 and human antibody FR2 inthe sense direction and the primer E should have a sequence hybridizingto the CDR1 and human antibody FR1 in the antisense direction (FIG.2(1)). Similarly, the grafting primers C and F and the primers D and Gare synthesized. Further, suitable primers, called “external primers”and corresponding to A and H in FIG. 2(1), which can hybridize to theregions upstream from FR1 and downstream from FR4, respectively, arealso synthesized. Isolation and extraction of the grafting primers maybe carried out in known procedures: Sambrook, et al., Molecular Cloning:A Laboratory Manual, Cold Spring Harbor Laboratory Press, 1989.

Then, frist PCR is performed using the grafting primer E and externalprimer A, the grafting primers B and F, the grafting primers C and G aswell as the grafting primer D and external primer H resulting in theformation of fragements A-E, B-F, C-G and D-H, respectively, (FIG.2(2)).

Since the upstream region of the grafting primer B and a part of thedownstream region of the grafting primer E have been designed to overlapwith each other (the same being true in the grafting primers C and F aswell as D and G), these fragments may be annealed with respectivecomplementary sequences by reacting under suitable temperatureconditions and assembled to a DNA having a length from A to H by PCR.Once a DNA fragment coding for the V region is obtained, the externalprimers A and H may be added and second PCR may be performed to yield aDNA coding for the V region of a humanized antibody in which FRs 1 to 4are human derived and CDRs 1 to 3 are mouse derived. Then, it may beintroduced into a suitable host to express to yield the desiredpolypeptide (FIG. 2(3)).

(ii) Construction of DNA and Experssion Vector Coding for Humanized HChain V Region

In the present invention, the whole base sequence of a DNA coding for Hchain V region of a human antibody to be used as a template for ahumanized antibody may be synthesized by a DNA synthesizer andconstructed by PCR method although said DNA is not available from thenatural source.

The H chain V region of a mouse anti-human PTHrP monoclonal antibody hasa high homology with S31679 belonging to human subgroup III. In order toemploy this human antibody as a template to construct a DNA coding for ahumanized H chain V region, four primers as shown in SEQ ID NOs:23-26,for example, are used. The primers MBC1HGP1 (SEQ ID NO:23) and MBC1HGP3(SEQ ID NO:24) have sense DNA sequences and MBC1HGP2 (SEQ ID NO:25) andMBC1HGP4 (SEQ ID NO:26) have antisense DNA sequences. They are designedto each have a 15 to 21 bp complementary sequence at either end thereof.

External primers MBC1HVS1 (SEQ ID NO:27) and MBC1HVR1 (SEQ ID NO:28)have a homologous sequence with MBC1HGP1 and MBC1HGP4, respectively, andeach comprises a recognition sequence for a respective suitablerestriction enzyme. The four primers are assemled by PCR method tosynthesize a full length cDNA, and the external primers are added toamplify the DNA. The “assemling by PCR method” herein involves annealingMBC1HGP1 and MBC1HGP2 or MBC1HGP3 and MBC1HGP4 through theircomplementary sequences to synthesize a MBC1HGP1-MBC1HGP3 fragment and aMBC1HGP2-MBC1HGP4 fragment and further annealing the fragments throughtheir complementary sequences to synthesize the full length DNA for ahumanized H chain V region.

Human antibody H chain C region may be any human H chain C region suchas, for example, human H chain Cγ1, Cγ2, Cγ3 or Cγ4.

The DNA for H chain V region of a humanized antibody constructed asabove described may be ligated to DNA for any human antibody H chain Cregion, for example, human H chain Cγ1 region. As mentioned in thesection “Production of H chain of chimeric antibody”, the DNA for Hchain V region may be treated with a suitable restriction enzyme andligated to a DNA coding for a human H chain C region under an expressioncontrol region such as an enhancer/promoter system to make an expressionvector containing DNAs for a humanized H chain V region and a human Hchain C region.

(iii) Construction of DNA and Experssion Vector Coding for Humanized LChain V Region

In the present invention, the whole base sequence of DNA coding for Lchain V region of a human antibody to be used as a template may besynthesized by a DNA synthesizer and constructed by PCR method althoughthe DNA for L chain V region is not available as in the case of the DNAcoding for H chain V region.

In order to construct a DNA for a humanized L chain V region using as atemplate a human antibody SU03868 having a highest homology with the Lchain V region of a mouse anti-human PTHrP monoclonal antibody, fourprimers as shown in SEQ ID NOs:29-32, for example, are used. The primersMBC1LGP1 (SEQ ID NO:29) and MBC1LGP3 (SEQ ID NO:30) have sense DNAsequences and MBC1LGP2 (SEQ ID NO:31) and MBC1LGP4 (SEQ ID NO:32) haveantisense DNA sequences. They are designed to each have a 15 to 21 bpcomplementary sequence at either end thereof.

External primers MBC1LVS1 (SEQ ID NO:33) and MBC1LVR1 (SEQ ID NO:34)have a homologous sequence with MBC1LGP1 and MBC1LGP4, respectively, andeach comprises a recognition sequence for a respective suitablerestriction enzyme. The four primers are assemled by PCR method tosynthesize a full length DNA, and the external primers are added toamplify the DNA. The “assemling by PCR method” herein involves annealingMBC1LGP1 and MBC1LGP3 or MBC1LGP2 and MBC1LGP4 through theircomplementary sequences to synthesize a MBC1LGP1-MBC1LGP3 fragment and aMBC1LGP2-MBC1LGP4 fragment and further annealing the fragments throughtheir complementary sequences to synthesize a full length DNA coding fora humanized H chain V region.

Human antibody L chain C region may be any human L chain C region suchas, for example, human L chain Cλ or Cκ.

The DNA for L chain V region of a humanized antibody constructed asabove described may be ligated to DNA for any human antibody L chain Cregion, for example, human L chain Cλ region. The DNA for L chain Vregion may be treated with a suitable restriction enzyme and ligated toa DNA coding for a human Lλ chain C region under an expression controlregion such as an enhancer/promoter system to make an expression vectorcontaining DNAs coding for a humanized L chain V region and a human Lλchain C region.

Even if a polypeptide comprising a V region of a humanized antibodycould be produced as above described, it is not necessarily clearwhether or not said polypeptide would have an activity as an antibody,such as binding or neutralizing activity against its antigen.Particularly in the case of L chain, since the L chain V region of amouse anti-human PTHrP monoclonal antibody is derived from a very rareVλx gene, it should be necessary to investigate the presence or absenceof the activity by combining it with a humanized H chain and expressingin an animal cell such as COS-7.

As a method for elucidating which FR in a humanized antibody V regionmay contribute to the binding and neutralizing activity of the humanizedantibody, construction of a hybrid V region (Ohtomo, T. et al.,Molecular Immunology, 32, 407-416, 1995) and confirmation may beeffective. In order to elucidate which amino acid in the L chain Vregion of the humanized antibody according to the present inventionshould be mutated to provide one having the activity, a DNA in which afragment of an FR region of a humanized antibody is recombined with afragment of a mouse derived FR region is constructed and each region isassessed for humanization.

As shown in FIG. 3, an antibody having a polypeptide comprising arecombinant V region in which FR1 and FR2 are derived from a humanantibody and FR3 and FR4 are derived from a mouse antibody (such anantibody having a recombinant fragment being referred to as a “hybridantibody”), a hybrid antibody in which only FR1 is human derived, and ahybrid antibody in which only FR2 is human derived, are made. Each ofDNAs coding for these hybrid antibodies is introduced into an expressionvector and the humanized antibodies are temporarily expressed toinvestigate the presence of antibody activities.

Using this method, the present inventor has investigated polypeptidescomprising L chain V regions for antigen binding and neutralizingactivities and finally found that certain amino acids to be replacedexist in FR2 and FR3.

Having found that amino acids contributing to the activity exist in FR2and FR3 regions, the present inventor has elucidated that the 36th, 45thand 49th amino acids in FR2 region and the 87th amino acid in FR3 region(the numbering of amino acids of antibodies having been determined byKabat, E. A. et al., US Dep. Health and Human Services, US GovernmentPrinting Offices, 1991) contribute to the activity.

Thus, a polypeptide comprising a V region in which such amino acid(s)is/are mutated (e.g., replaced) is made in the present invention.

First, a polypeptide comprising a V region having an amino acid sequenceas a base into which a mutation of amino acid(s) is to be introduced isprepared by the aforementioned CDR-grafting. This base polypeptidecomprises the amino acid sequence as shown in SEQ ID NO:47 and isreferred to as “version a” (a in Table 1).

Then, from the version a as a base, various variant fragments in whichone or some amino acids of FR are mutated are made.

The introduction of mutation may be carried out by designing anoligonucleotide primer (mutagenic primer) coding for an amino acid to beintroduced as a desired mutation and performing PCR using said primer.

Thus, polypeptides comprising V regions (versions b to t) in which aspecific amino acid(s) in FR2 and FR3 is/are mutated are made (b to t inTable 1).

Table 1:

TABLE 1 FR1                                  CDR1         1         2         3 123456789012345678901234567890    12345MBC H. PEP EVQLVESGGDLVKPGGSLKLSCAASGFTFS    SYGMS *        ** *  *  *S31679 QVQLVESGGGVVQPGRSLRLSCAASGFTFS    SYAMH hMBC1-H. pep------------------------------    SYGMS FR2               CDR2    4             5          6 67890123456789    012A3456789012345 MBCH. PEP WIRQTPDKRLEWVA    TISSGGSYTYYPDSVKG  *  * * * S31679WVRQAPGKGLEWVA    VISYDGSNKYYADSVKG hMBC1-H. pep--------------    TISSGGSYTYYPDSVKGFR3                                CDR3         FR47          8            9              10             1167890123456789012ABC345678901234   567890A12    34567890123 MBC H. PEPRFTISRDNAKNTLYLQMSSLKSEDTAMFYCAR   QTTMTYFAY    WGQGTLVTVSA        *        *  **    **                              * S31679RFTISRDNSKNTLYLQMNSLRAEDTAVYYCAR   ESRGDY       WGQGTLVTVSS hMBC1-H. pep--------------------------------   QTTMTYFAY    -----------FR1                        CDR1            FR2               CDR2         1         2              3             4            512345678901234567890123    4567A8901234    567890123456789   01234ABCD56MBC L. PEP QLVLTQSSS-ASFSLGASAKLTC   TLSSQHSTYTIE    WYQQQPLKPPKYVMD   LKQDGSHSTGD       *    *     *                         *    * * * * * HSU03868QLVLTQSPS-ASASLGASVKLTC    TLSSGHSSYAIA    WHQQQPEKGPRYLMK   LNSDGSHSKGDhMBC1-L. pep-----------------------    TLSSQHSTYTIE    ---------------   LKQDGSHSTGDa-----------------------    ------------    ---------------   -----------b-----------------------    ------------    --------P-----D   -----------c-----------------------    ------------    ---------------   -----------d-----------------------    ------------    ---------------   -----------e-----------------------    ------------    --------P-----D   -----------f-----------------------    ------------    ---------------   -----------g-----------------------    ------------    -Y-------------   -----------h-----------------------    ------------    -Y-------------   -----------i-----------------------    ------------    -Y--------K----   -----------j-----------------------    ------------    -Y--------K---D   -----------k-----------------------    ------------    -Y--------K-V--   -----------l-----------------------    ------------    -Y--------K-V-D   -----------m-----------------------    ------------    -Y------------D   -----------n-----------------------    ------------    -Y----------V--   -----------o-----------------------    ------------    -Y----------V-D   -----------p-----------------------    ------------    -Y--------K----   -----------q-----------------------    ------------    -Y--------K---D   -----------r-----------------------    ------------    -Y------------D   -----------s-----------------------    ------------    -Y--------K-V-D   -----------t-----------------------    ------------    -Y----------V-D   -----------FR3                                  CDR3               FR4   6         7         8              9                  10         1178901234567890123456789012345678     9012345ABCD67      890123456A7890MBC L. PEPGIPDRFSGSSSGADRYLSISNIQPEDEAMYIC     GVGDTIKEQFVYV      FGGGTKVTVLGQP             *   *  ** *    * * HSU03868GIPDRFSGSSSGAERYLTISSLQSEDEADYYC     QTWGTGI hMBC1-L. pep--------------------------------     GVGDTIKEQFVYV      ------L------ a--------------------------------     -------------      ------L------ b--------------------------------     -------------      ------L------ c-----------------------P--------     -------------      ------L------ d------------------------------I-     -------------      ------L------ e------------------------------I-     -------------      ------L------ f-----------------------P------I-     -------------      ------L------ g--------------------------------     -------------      ------L------ h------------------------------I-     -------------      ------L------ i--------------------------------     -------------      ------L------ j--------------------------------     -------------      ------L------ k--------------------------------     -------------      ------L------ l--------------------------------     -------------      ------L------ m--------------------------------     -------------      ------L------ n--------------------------------     -------------      ------L------ o--------------------------------     -------------      ------L------ p------------------------------I-     -------------      ------L------ q------------------------------I-     -------------      ------L------ r------------------------------I-     -------------      ------L------ s------------------------------I-     -------------      ------L------ t------------------------------I-     -------------      ------L------

The DNA cording for each version of L chain V region of a humanizedantibody as constructed above may be ligated to a DNA of any L chain Cregion of a human antibody, such as human L chain Cλ region. Thus, it istreated with a suitable restriction enzyme and ligated to a DNA codingfor a human Lλ chain C region under the control of an expression controlregion such as an enhancer/promoter system to construct an expressionvector comprising a DNA coding for each version of the humanized L chainV region and a DNA coding for the humanized Lλ chain C region.

The DNA coding for H chain V region of a humanized antibody and a humanH chain C region as previously constructed and the DNA coding for ahumanized L chain V region and human L chain C region may also beintroduced into a single expression vector such as that disclosed inWO94/11523, said vector may be used to transform a host cell, and thetransformed host may be cultivated in vivo or in vitro to produce adesired humanized antibody.

4. Production of Chimeric Antibody and Humanized Antibody

To produce a chimeric or humanized antibody, two expression vectors asabove mentioned should be prepared. Thus, with respect to a chimericantibody, an expression vector comprising a DNA coding for a mouse Hchain V region and a human H chain C region under the control of anexpression control region such as an enhancer/promoter system, and anexpression vector comprising a DNA coding for a mouse L chain V regionand a human L chain C region under the control of an expression controlregion such as an enhancer/promoter system are constructed. With respectto a humanized antibody, an expression vector comprising a DNA codingfor a humanized H chain V region and a human H chain C region under thecontrol of an expression control region such as an enhancer/promotersystem, and an expression vector comprising a DNA coding for a humanizedL chain V region and a human L chain C region under the control of anexpression control region such as an enhancer/promoter system areconstructed.

Then, a host cell such as a mammalian cell is cotransformed with theseexpression vectors and the resulting transformed cell is cultivated invitro or in vivo to produce the chimeric or humanized antibody (see, forexample, WO91/16928).

Alternatively, a DNA coding for H chain V and C regions and a DNA codingfor L chain V and C regions may be ligated to a single vector andtransformed into a suitable host cell to produce an antibody. Thus, inthe expression of a chimeric antibody, a DNA coding for a mouse leadersequence present in the cloned cDNA, a mouse H chain V region and ahuman H chain C region as well as a DNA coding for a mouse leadersequence, a mouse L chain V region and a human L chain C region, areintroduced into a single expression vector such as one disclosed in e.g.WO94/11523. In the expression of a humanized antibody, a DNA coding fora humanized H chain V region and a human H chain C region and a DNAcoding for a humanized L chain V region and a human L chain C region areintroduced into a single expression vector such as one disclosed in e.g.WO94/11523. Such a vector is used to transform a host cell and thetransformed host is cultivated in vivo or in vitro to produce a chimericor humanized antibody of interest.

The chimeric or humanized antibody of interest which is thus produced bycultivating the transformant transformed with a DNA coding for saidchimeric or humanized antibody may be isolated from the interior orexterior of the cell and purified to uniformity.

The isolation and purification of the chimeric or humanized antibody ofinterest according to the present invention may be carried out by usinga protein A agarose column, but may also be performed by any methodsused in isolation and purification of conventional proteins and thus isnot limited. For instance, various chromatography, ultrafiltration,salting out and dialysis may optionally be selected or combined toisolate and purify the chimeric or humanized antibody.

Any expression system may be used to produce the chimeric or humanizedantibody against human PTHrP according to the present invention. Forexample, eukaryotic cells include animal cells such as establishedmammalian cell lines, mold and fungal cells, and yeast cells;prokaryotic cells include bacterial cells such as Escherichia colicells. Preferably, the chimeric or humanized antibody of the presentinvention is expressed in a mammalian cell such as COS or CHO cell.

Any conventional promoters useful for the expression in mammalian cellsmay be used. For example, human cytomegalovirus immediate early (HCMV)promoter is preferably used. Examples of expression vectors comprisingHCMV promoter include HCMV-VH-HCγ1 and HCMV-VL-HCK derived from pSV2neo(WO92/19759).

In addition, promoters for gene expression in mammalian cells which canbe used in the present invention may include virus promoters, such asthose of retrovirus, polyoma virus, adenovirus and simian virus (SV) 40,and mammalian cell derived promoters, such as those of human polypeptidechain elongation factor-1α (HEF-1α). For example, SV40 promoter may bereadily used according to Mulligan et al. method (Nature, 277, 108,1979); Mizushima, S. et al. method (Nucleic Acids Research, 18, 5322,1990) may be easily used with HEF-1α promoter.

Origin of replication usable herein includes those derived from SV40,polyoma virus, adenovirus or bovine papilloma virus (BPV). Further, theexpression vector may comprise a gene for phosphotransferase APH(3′) IIor I (neo), thymidine kinase (TK), E. coli xanthine-guaninephosphoribosyltransferase (Ecogpt) or dihydrofolate reductase (DHFR) asa selective marker for increasing the gene copy number in a host cellsystem.

5. Evaluation of Antigen Binding and Neutralizing Activity of Chimericand Humanized Antibodies

(1) Determination of Antibody Concentration

The concentration of the resulting purified antibody can be determinedby ELISA.

ELISA plates for determining the antibody concentration are prepared inthe following manner: 100 μl of a goat anti-human IgG antibody preparedat a concentration of e.g. 1 μg/ml is immobilized in each well of a 96well plate for ELISA (for example, Maxisorp, NUNC). After blocking with200 μl of a diluting buffer (for example, 50 mM Tris-HCl, 1 mM MgCl₂,0.1 M NaCl, 0.05% Tween20, 0.02% NaN₃, 1% bovine serum albumin (BSA), pH7.2), a stepwise diluted supernatant of COS-7 or CHO cells in which thechimeric, hybrid or humanized antibody has been expressed, or purifiedchimeric, hybrid or humanized antibody is added to each well, 100 μl ofan alkaline phosphatase-conjugated goat anti-human IgG antibody isadded, and 1 mg/ml of a substrate solution (Sigma 104,p-nitrophenylphosphoric acid, SIGMA) is then added, after which theabsorbance at 405 nm is measured by a microplate reader (Bio Rad). HuIgG1λ Purified (The Binding Site) may be used as a standard for thedetermination of concentrations.

(2) Determination of Antigen Binding Ability

ELISA plates for determining the antigen binding ability are prepared inthe following manner: 100 μl of human PTHrP (1-34) prepared at aconcentration of 1 μg/ml is immobilized to each well of a 96 well platefor ELISA. After blocking with 200 μl of a diluting buffer, a stepwisediluted supernatant of COS-7 or CHO cells in which the chimeric, hybridor humanized antibody has been expressed, or purified chimeric, hybridor humanized antibody is added to each well, 100 μl of an alkalinephosphatase-conjugated goat anti-human IgG antibody is added, and 1mg/ml of a substrate solution (Sigma 104, p-nitrophenylphosphoric acid,SIGMA) is then added, after which the absorbance at 405 nm is measuredby a microplate reader (BioRad).

(3) Determination of Neutralizing Activity

Determination of the neutralizing activity of the mouse, chimeric andhumanized antibodies can be carried out by, e.g., using rat osteosarcomacell line ROS17/2.8-5 cell (Sato, K. et al., Acta Endocrinology, 116,113-120, 1987). Thus, ROS17/2.8-5 cells are stimulated by 4 mMhydrocortisone to induce PTH/PTHrP receptor. The degradative enzyme forcAMP is inhibited with 1 mM of isobutyl-1-methyl xanthine (IBMX, SIGMA).The mouse, chimeric or humanized antibody to be determined forneutralizing activity is mixed with an equal amount of PTHrP (1-34) andthe resulting mixture of each antibody and PTHrP (1-34) is added to eachwell. The neutralizing ability of the mouse, chimeric or humanizedantibody can be estimated by measuring the amount of cAMP produced byrat osteosarcoma cell lines ROS17/2.8-5 cells due to stimulation withPTHrP.

(4) Kinetic Analysis of Interactions Between PTHrP and Anti-PTHrPAntibody

In the present invention, the kinetics in the interactions between PTHrPand anti-PTHrP may be analyzed by a variety of means and procedures.Specifically, dissociation constants, dissociation rate constants andassociation rate constants may be measured by Scatchard analysis and asurface plasmon resonance sensor called BIACORE (developed andcommercialized by Pharmacia Biotech). Analysis by a surface plasmonresonance sensor called BIACORE will be described hereininbelow as oneexample.

The basic structure of BIACORE comprises an optical source, a prism, adetector and a micro-passage. In practice, a ligand is immobilized on acassette-type sensor tip and an analyte is injected thereinto. Whenthere is any affinity between them, the binding amount is opticallydetected.

The detecting principle is a phenomenon called surface plasmonresonance. Thus, of incident light injected to the interface between aglass and a metal film so that total reflection should occur, theincident light at a certain angle is used to excite surface plasmon anddamped. The angle vary depending upon the change in concentration of asolvent in contact with the metal film (sensor). BIACORE detects thischange.

In BIACORE, this change is called a resonance signal (SPR signal) and achange of 0.1 degree is 1000 RU (resonance units). 1000 RU correspondsto a change in the binding of about 1 ng of a protein onto a thin goldsensor of 1 mm² in surface area. For a protein, a change of about 50 RU(50 pg) can be fully detected.

The detected signals are converted into a binding curve called asonsorgram by a computor attached to BIACORE, which is drawn on acomputor display in real time: Natsume, T., et al. (1995) ExperimentalMedicine, 13, 563-569; Karlsson, R., et al. (1991) J. Immunol. Methods145, 229-240.

Kinetics parameters, i.e., dissociation constant (KD), dissociation rateconstant (Kdiss) and association rate constant (Kass), of the anti-PTHrPantibodies of the present invention may be measured by the abovementioned BIACORE.

The anti-PTHrP antibodies of the present invention preferably have assmall a dissociation constant (KD value) as possible in view ofneutralizing activity. Preferably, the anti-PTHrP antibodies of thepresent invention have a KD value 1.86×10⁻⁷ or less, more preferably1.86×10⁻⁸ or less, most preferably 3.58×10⁻¹⁰ or less.

The KD values are determined from two parameters, dissociation rateconstants (Kdiss) and association rate constants (Kass) (KD=Kdiss/Kass).Apparently, therefore, the KD values are smaller when the Kdiss valuesare smaller and the Kass values are larger.

Specifically, the Kdiss values of the anti-PTHrP antibodies according tothe present invention may be 1.22×10⁻¹ [l/Sec] or less. Preferably, theKdiss values are 1.22×10⁻² or less, more preferably 3.16×10⁻⁴ or less,most preferably 2.32×10⁻⁴ [l/Sec] or less.

On the other hand, the Kass values may be 6.55×10⁴ [l/M.Sec] or more.Preferably, the Kass values are 6.55×10⁵ or more, more preferably0.883×10⁶ or more, most preferably 1.03×10⁶ [l/M.Sec] or more.

Further, also preferred are anti-PTHrP antibodies having a Kdiss valueof 1.22×10⁻¹ [l/Sec] and a Kass value of 6.55×10⁴ [l/M.Sec] or more.

More specifically, the anti-PTHrP antibodies of the present inventionhave a KD value in the range of 1.02×10⁻¹¹ to 1.86×10⁻⁷ [M], preferably1.02×10⁻¹⁰ to 1.86×10⁻⁸ [M], more preferably 1.34×10⁻¹⁰ to 3.58×10⁻¹⁰[M], most preferably 2.25×10⁻¹⁰ to 3.58×10⁻¹⁰ [M].

The Kdiss values are in the range of 7.38×10⁻⁶ to 1.22×10⁻¹ [l/Sec],preferably 7.38×10⁻⁵ to 1.22×10⁻² [l/Sec], more preferably 1.66×10⁻⁴ to3.16×10⁻⁴ [l/Sec], most preferably 1.66×10⁻⁴ to 2.32×10⁻⁴ [l/Sec].

The Kass values are in the range of 6.55×10⁴ to 1.24×10⁷ [l/M.Sec],preferably 6.55×10⁵ to 1.24×10⁶ [l/M.Sec], more preferably 7.23×10⁵ to1.03×10⁶ [l/M.Sec], most preferably 0.883×10⁶ to 1.03×10⁶ [l/M.Sec].

These KD, Kdiss and Kass values may be obtained by Scatchard analysis ora surface plasmon resonance sensor such as BIACORE, preferably byBIACORE.

6. Pharmaceutical Composition and Hypercalcemia-Suppressing AgentComprising Anti-PTHrP or Humanized Antibody as Effective Ingredient.

The therapeutic effect of the humanized antibody on PTHrP may beconfirmed by administering the antibody against PTHrP or the humanizedantibody to an animal exhibiting hypercalcemia and measuring an indexfor hypercalcemia. In animals exhibiting hypercalcemia and patientssuffering from hypercalcemia, hypophosphatemia is often observed; theantibodies of the present invention may also be used to improve thehypophosphatemia.

The antibody used in the present invention is an anti-PTHrP antibodyincluding human, chimeric and primatized antibodies or a humanizedantibody against PTHrP having the dissociation constant, dissociationrate constant and association rate constant. The antibody willneutralize the activity of PTHrP by binding to PTHrP and preferablyincludes, in particular, humanized #23-57-137-1 antibody. The method forproducing the humanized #23-57-137-1 antibody will be described inExamples 1 to 3.

The antibody used in the present invention can be purified to a highpurity by any combination of conventional purification means such assalting out, gel filtration using HPLC etc., and affinity chromatographyusing a protein A column etc. Recognition of PTHrP by the thus purifiedantibody with a high accuracy may be confirmed by any conventionalimmunological means such as radioimmunoassay (RIA), enzyme immunoassay(EIA, ELISA) or immunofluorescence analysis.

The animal exhibiting hypercalcemia which may be used includes a modelanimal prepared by transplanting PTHrP-producing tumor cells to anexperimental animal with reduced or deleted immunological function. Thetumor cells transplanted are preferably human derived ones including,for example, human pancrea cancer PAN-7. The animal with reduced ordeleted immunological function to which the tumor cells are transplantedincludes nude mouse and SCID mouse.

Suppression of hypercalcemia may be evaluated by observing theconcentration of calcium in the blood, the reduction of body weight orthe reduction of extent of movement with the lapse of time anddetermining the degree of improvement.

The pharmaceutical composition and hypercalcemia suppressing agentcomprising the antibody or humanized antibody against PTHrP as aneffective ingredient according to the present invention may beparenterally administered systemically or topically. For example,intravenous injection including drip, intramuscular injection,intraperitoneal injection or subcutaneous injection may be selected. Themethod of administration may be properly selected depending on the ageof a patient and the conditions of disease. An effective single dose maybe selected from the range of 0.01 to 1,000 mg per kg of body weight.Alternatively, the dose to a patient may be 5 to 10,000 mg/body,preferably 50 to 1,000 mg/body.

The pharmaceutical composition and hypercalcemia suppressing agentcomprising the antibody or humanized antibody against PTHrP as aneffective ingredient according to the present invention may furthercomprise a pharmaceutically acceptable carrier and/or additive(s)depending upon the administration route. Examples of such carrier andadditive may include water, pharmaceutically acceptable organicsolvents, collagen, polyvinyl alcohol, polyvinyl pyrrolidone,carboxyvinyl polymer, sodium carboxymethyl cellulose, poly(sodiumacrylate), sodium arginate, water soluble dextran, sodium carboxymethylstarch, pectin, methyl cellulose, ethyl cellulose, xanthane gum, gumarabic, casein, gelatin, agar, diglycerin, glycerin, propylene glycol,polyethylene glycol, vaseline, paraffin, stearyl alcohol, stearic acid,human serum albumin (HSA), mannitol, sorbitol, lactose, and surfactantsacceptable as pharmaceutical additives. The additives used may beproperly selected from the above either alone or in combination, but notlimited thereto.

The antibody of the present invention may be used widely inhypercalcemia associated with various cancers (malignant tumors). Thesecancers are not particularly limited and include not only a singlecancer but also a combination of a plurality of cancers. The cancers mayinclude for example pancreas, lung, pharynx, larynx, tongue, gingiva,esophagus, stomach, biliary duct, breast, kidney, urinary bladder,uterus and prostate cancers, and malignant lymphoma.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic illustration of the antibody according to thepresent invention;

FIG. 2 is a schematic illustration of the CDR-grafting;

FIG. 3 is an illustration of the determination of the FRs and the CDRsof the V region;

FIG. 4 is a graph showing the measurement result of the antigen-bindingactivity of the antibodies;

FIG. 5 is a graph showing the measurement result of the antigen-bindingactivity of the antibodies;

FIG. 6 is a graph showing the measurement result of the antigen-bindingactivity of the antibodies;

FIG. 7 is a graph showing the measurement result of the antigen-bindingactivity of the antibodies;

FIG. 8 is a graph showing the measurement result of the antigen-bindingactivity of the antibodies;

FIG. 9 is a graph showing the measurement result of the antigen-bindingactivity of the antibodies;

FIG. 10 is a graph showing the measurement result of the antigen-bindingactivity of the antibodies;

FIG. 11 is a graph showing the measurement result of the antigen-bindingactivity of the antibodies;

FIG. 12 is a graph showing the neutralizing activity of the humanizedantibodies;

FIG. 13 is a graph showing the neutralizing activity of the humanizedantibodies;

FIG. 14 is a graph showing the neutralizing activity of the humanizedantibodies;

FIG. 15 are graphs illustrating the efficacy of the antibodies of thepresent invention against a hypercalcemic model animal;

FIG. 16 are graphs illustrating the efficacy of the antibodies of thepresent invention on a hypercalcemic model animal;

FIG. 17 are graphs illustrating the efficacy of the antibodies of thepresent invention on a hypercalcemic model animal;

FIG. 18 are graphs illustrating the efficacy of the antibodies of thepresent invention on a hypercalcemic model animal;

FIG. 19 is a sensorgram illustrating the immobilization of PTHrP ontosensor tip;

FIG. 20 is a graph showing the results of the kinetic analysis of theantibody according to the invention;

FIG. 21 is a graph showing the results of the kinetic analysis of theantibody according to the invention;

FIG. 22 is a graph showing the results of the kinetic analysis of theantibody according to the invention;

FIG. 23 is a graph showing the results of the kinetic analysis of theantibody according to the invention;

FIG. 24 is a graph showing the results of the kinetic analysis of theantibody according to the invention;

FIG. 25 is a graph showing the test results of the effect of thehumanized antibody according to the invention on fractional excretion ofphosphate;

FIG. 26 is a graph showing the test result of the effect of thehumanized antibody according to the invention on phosphorusconcentration in plasma;

FIG. 27 is a photograph showing the apparent clinical symptoms ofhypercalcemia model mice developed after administration of theanti-PTHrP antibody according to the invention (morphology of livinganimal);

FIG. 28 is a photograph showing the apparent clinical symptoms ofhypercalcemia model mice developed after administration of theanti-PTHrP antibody according to the invention (morphology of livinganimal);

FIG. 29 is a graph showing the change in spontaneous activity of ahypercalcemia model animal over time after administering the anti-PHTHrPantibody according to the invention in comparison with that of a controlmodel animal administered with physiological saline;

FIG. 30 is a graph showing the change in body temperature of ahypercalcemia model animal over time after administering the anti-PHTHrPantibody according to the invention in comparison with that of a controlmodel animal administered with physiological saline; and

FIG. 31 is a graph showing the change in blood pH of a hypercalcemiamodel animal over time after administering the anti-PHTHrP antibodyaccording to the invention in comparison with that of a control modelanimal administered with physiological saline.

EXAMPLE

Hereinbelow, the present invention will be described in more detail withreference to the following Examples, which should not be construed aslimiting the scope of the invention.

Reference Example 1 Preparation of Anti-PTHrP (1-34) Mouse MonoclonalAntibody Producing Hybridoma

Hybridomas capable of producing a monoclonal antibody against humanPTHrP (1-34), #23-57-154 and #23-57-137-1, were prepared in accordancewith the method reported by Kanji Sato et al. (Sato, K. et al., J. BoneMiner. Res. 8, 849-860, 1993).

The immunogen used was PTHrP (1-34) (Peninsula), to which a carrierprotein, thyroglobulin, was conjugated using carbodiimide (Dojinn). Thethycloglobulin-conjugated PTHrP (1-34) was dialyzed to obtain a solutionhaving a protein concentration of 2 μg/ml. The resultant solution wasmixed with Freund's adjuvant (Difco) in a mixing ratio of 1:1 to obtainan emulsion. This emulsion was injected to each of 16 female BALB/C micedorsal-subcutaneously or intraperitoneally in a dose amount of 100μg/mouse to immunize the mice. The injection was conducted 11 times.With respect to the adjuvant, Freund's complete adjuvant was used in theinjection for the first immunization, and Freund's incomplete adjuvantwas used in the injection for subsequent immunizations.

Each of the mice immunized was determined for its antibody titers in thesera in the following manner:

Each of the mice was blood-drawn from its tail vein and the blood wasthen subjected to centrifugation to obtain a serum. The serum wasdiluted with a RIA buffer, mixed with ¹²⁵I-labeled PTHrP (1-34), andsubjected to determination of its binding activity. The mice which havebeen confirmed to have a satisfactorily high antibody titer wereinjected with PTHrP (1-34) without the carrier protein intraperitoneallyin a dose amount of 50 μg/mouse for the final immunization.

Three days after the final immunization, the mice were sacrificed andexcised their spleens. Thereafter, spleen cells were subjected to cellfusion with mouse myeloma cell line P3x63Ag8U.1 in accordance with aconventional known method using 50% polyethylene glycol 4000. The fusedcells thus prepared were inoculated into each well of 85 of 96-wellplates in an amount of 2×10⁴/well. The screening of hybridomas ofinterest was conducted using a HAT medium as follows.

The screening of the hybridomas was conducted by determining for thepresence of PTHrP-recognition antibodies in the culture supernatant withrespect to the wells in which cell growth had been observed in the HATmedium by a solid phase RIA method. The hybridomas were collected fromthe wells in which the binding ability to the PTHrP-recognition antibodywas confirmed. The hybridomas thus obtained was suspended into aRPMI-1640 medium containing 15% FCS and supplemented with OPI-supplement(Sigma), followed by unification of the hybridomas by a limitingdilution method, thereby obtaining two types of hybridoma clones,#23-57-154 and #23-57-137-1 both exhibiting a strong binding ability toPTHrP (1-34).

Hybridoma clone #23-57-137-1, which was designated “mouse-mousehybridoma #23-57-137-1”, has been deposited under the terms of theBudapest Treaty on Aug. 15, 1996 at the National Institute of Bioscienceand Human-technology, Agency of Industrial Science and Technology, Japan(1-3, Higashi 1-chome, Tsukuba-shi, Ibaragi-ken, Japan) under theaccession No. FERM BP-5631.

Example 1 Cloning of DNA Coding for V Region of Mouse MonoclonalAntibody Against Human PTHrP (1-34)

Cloning of the DNA coding for the V region of the mouse monoclonalantibody against human PTHrP (1-34) obtained above, #23-57-137-1, wasconducted in the following manner.

(1) Preparation of mRNA

mRNA was prepared from hybridoma #23-57-137-1 using Quick Prep mRNAPurification Kit (Pharmacia Biotech) as follows.

The cells of hybridoma #23-57-137-1 obtained above were fullyhomogenized with an extraction buffer, and mRNA was extracted therefromusing an oligo(dT)-Cellulose Spun Column in accordance with theprocedure by the manufacturer of the kit. The extraction solution wassubjected to ethanol precipitation to obtain the mRNA as precipitates.The mRNA precipitates were dissolved in an elution buffer.

(2) Preparation and Amplification of cDNA of the Gene Coding for Mouse HChain V Region

(i) Cloning of cDNA for H Chain V Region of #23-57-137-1 Antibody

A DNA coding for the H chain V region of the mouse monoclonal antibodyagainst human PTHrP was cloned by a 5′-RACE method (Frohman, M. A. etal., Proc. Natl. Acad. Sci. USA, 85, 8998-9002, 1988; Belyavsky, A. etal., Nucleic Acids Res. 17, 2919-2932, 1989). This method was conductedusing 5′-Ampli FINDER RACE Kit (CLONETECH) in accordance with theprocedure by the manufacturer. In this method, the primer used forsynthesis of cDNA was MHC2 primer (SEQ ID NO: 1) which is hybridizablewith mouse H chain C region. About 2 μg of the above-obtained mRNA,which was a template for cDNA synthesis, was mixed with 10 pmoles ofMHC2 primer. The resultant mixture was reacted with a reversetranscriptase at 52° C. for 30 min to prepare a cDNA which wascomplementary to the mRNA.

The resultant was mixed with 6N NaOH to hydrolyze the mRNA therein (at65° C. for 30 min.) and then subjected to ethanol precipitation toisolate the cDNA as precipitates. The cDNA thus isolated was ligated toAmpli FINDER Anchor (SEQ ID NO: 42) on its 5′-end by reacting with T4RNA ligase at 37° C. for 6 hours and additionally at room temperaturefor 16 hours. As the primers for amplification of the cDNA by a PCRmethod, Anchor primer (SEQ ID NO: 2) and MHC-G1 primer (SEQ ID NO: 3)(S. T. Jones, et al., Biotechnology, 9, 88, 1991) were used.

The PCR solution (50 μl) used in this method comprised 10 mM Tris-HCl(pH 8.3), 50 mM KCl, 0.25 mM dNTPs (DATP, dGTP, dCTP, dTTP), 1.5 mMMgCl₂, 2.5 units of TaKaRa Taq (Takara Shuzo), 10 pmoles Anchor primer,and 1 μl of the reaction mixture of the cDNA to which MHC-G1 primer andAmpli FINDER Anchor primer had been ligated, over which 50 μl of mineraloil was layered. Thirty cycles of the PCR reaction was conducted usingThermal Cycler Model 480J (Perkin Elmer) and a temperature cycle of 94°C. for 45 sec.; 60° C. for 45 sec.; and 72° C. for 2 min.

(ii) Cloning of cDNA for #23-57-137-1 Antibody L Chain V Region

A DNA coding for L chain V region of the mouse monoclonal antibodyagainst human PTHrP was cloned by the 5′-RACE method (Frohman, M. A. etal., Proc. Natl. Acad. Sci. USA, 85, 8998-9002, 1988; Belyavsky, A. etal., Nucleic Acids Res. 17, 2919-2932, 1989). This method was conductedusing 5′-Ampli Finder RACE Kit (Clonetech) in accordance with theprocedure by the manufacturer. In this method, oligo-dT primer was usedas the primer for synthesizing a cDNA. About 2 μg of the above-mentionedmRNA (which was a template for cDNA synthesis) was mixed with oligo-dTprimer. The resultant mixture was reacted with a reverse transcriptaseat 52° C. for 30 min. to prepare a cDNA. The resultant was mixed with 6NNaOH to hydrolyze the RNA therein (at 65° C. for 30 min.). The resultantmixture was subjected to ethanol precipitation to isolate the cDNA asprecipitates. The cDNA thus synthesized was ligated to the Ampli FINDERAnchor on its 5′-end by reacting with T4 RNA ligase at 37° C. for 6hours and additionally at room temperature for 16 hours.

PCR primer MLC (SEQ ID NO: 4) was designed based on the conservedsequence of a mouse L chain λ chain C region and then synthesized using394 DNA/RNA Synthesizer (ABI). The PCR solution (100 μl) used for thesynthesis of the primer comprised 10 mM Tris-HCl (pH 8.3), 50 mM KCl,0.25 mM dNTPs (DATP, dGTP, dCTP, dTTP), 1.5 mM MgCl₂, 2.5 units ofAmpliTaq (PERKIN ELMER), 50 pmoles of Anchor primer (SEQ ID NO: 2), and1 μl of the reaction mixture of the cDNA to which MLC (SEQ ID NO: 4) andAmpli FINDER Anchor were ligated, over 50 μl of mineral oil was layered.Thirty-five cycles of the PCR reaction was conducted using ThermalCycler Model 480J (Perkin Elmer) and a temperature cycle of 94° C. for45 sec.; 60° C. for 45 sec.; and 72° C. for 2 min.

(3) Purification and Fragmentation of the PCR Product

Each of the DNA fragments amplified by the PCR methods described abovewas separated by agarose gel electrophoresis using 3% Nu Sieve GTGagarose (FMC Bio. Products). For each of the H chain V region and the Lchain V region, agarose gel fraction containing a DNA fragment of about550 bp in length was excised from the gel, respectively. Each of the gelfractions obtained was subjected to purification of the DNA therefromusing GENECLEAN II Kit (BIO101) in accordance with the procedure by themanufacturer. The purified DNA was precipitated from the solution withethanol and then dissolved in 20 μl of a solution containing 10 mMTris-HCl (pH 7.4) and 1 mM EDTA. One μl of the DNA solution thusprepared was digested with restriction enzyme XmaI (New England Biolabs)at 37° C. for 1 hour and additionally with restriction enzyme EcoRI(Takara Shuzo) at 37° C. for 1 hour. The digestion mixture was subjectedto extraction with phenol and chloroform and then precipitation withethanol to collect the DNA.

In this manner, obtained a DNA coding for the mouse H chain V region anda DNA coding for the mouse L chain V region, both which had an EcoRIrecognition sequence on the 5′-end and an XmaI recognition sequence onthe 3′-end thereof were obtained.

Each of the EcoRI-XmaI DNA fragments containing a DNA coding for themouse H chain V region and a DNA coding for the mouse L chain V region,respectively, was reacted with pUC19 vector, which had been digestedwith EcoRI and XmaI, at 16° C. for 1 hour using DNA Ligation Kit ver.2(Takara Shuzo) in accordance with the procedure by the manufacturer toligate to each other. The ligation mixture (10 μl) thus obtained wasadded to 100 μl of a solution containing competent cells of E. coli, JM109 (Nippon Gene). The cell mixture was allowed to stand for 15 min. onice, at 42° C. for 1 min. and further for 1 min. on ice. The resultantwas mixed with 300 μl of SOC culture medium (Molecular Cloning: ALaboratory Manual, Sambrook, et al., Cold Spring Harbor LaboratoryPress, 1989) and then incubated at 37° C. for 30 min. The resultant cellsolution was spread on a LB or 2xYT agar medium (Molecular Cloning: ALaboratory Manual, Sambrook, et al., Cold Spring Harbor LaboratoryPress, 1989) supplemented with 100 or 50 μg/ml of ampicillin, 0.1 mM ofIPTG and 20 μg/ml of X-gal and then incubated at 37° C. overnight. Inthis manner, E. coli transformants were prepared.

The transformants were cultured overnight in 2 ml of a LB or 2xYT mediumcontaining 100 or 50 μg/ml of ampicillin at 37° C. and then plasmid DNAwas prepared from the cell fraction using Plasmid Extracter PI-100Σ(Kurabou) or QIAprep Spin Plasmid Kit (QIAGEN). The plasmid DNAs thusobtained were determined for their DNA sequences.

(4) Sequencing of cDNA Coding for V Region of Mouse Antibody

The sequence of the cDNA coding region carried on the plasmid wasdetermined by DNA Sequencer 373A (ABI; Perkin-Elmer) using DyeTerminator Cycle Sequencing Kit (Perkin-Elmer). This DNA sequence wasdetermined by confirming the base sequence in the both orientationsusing primers, M13 Primer M4 (Takara Shuzo) (SEQ ID NO: 5) and M13Primer RV (Takara Shuzo) (SEQ ID NO: 6).

The plasmids thus obtained, which contained a cDNA coding for the mouseH chain V region and a cDNA coding for the mouse L chain V regionderived from hybridoma #23-57-137-1, were designated “MBC1H04” and“MBC1L24”, respectively. The sequences (including the correspondingamino acids sequences) of the DNA coding for the H chain V region andthe DNA coding for the L chain V region of mouse #23-57-137-1 antibody(respectively carried on plasmid MBC1H04 and plasmid MBC1H24) were shownin SEQ. ID NOs: 57 and 65, respectively. Both of the polypeptides forthe H chain V region fragment and for the L chain V region fragment weretranslated starting from the 58th base (which coding for glutamine) inthe DNA sequences shown in SEQ ID NOs: 57 and 65. The amino acidsequences for the H chain V region and the L chain V region were shownin SEQ. ID NOs: 46 and 45, respectively.

The E. coli having plasmid MBC1H04 and the E. coli having plasmidMBC1L24 were designated “Escherichia coli JM109 (MBC1H04)” and“Escherichia coli JM109 (MBC1L24)”, respectively. These E. coli strainshave been deposited under the terms of the Budapest Treaty at theNational Institute of Bioscience and Human-Technology, Agency ofIndustrial Science and Technology, Japan (1-3, Higashi 1-chome,Tsukuba-shi, Ibaragi-ken, Japan) on Aug. 15, 1996 under the AccessionNo. FERM BP-5628 for Escherichia coli JM109 (MBC1H04) and FERM BP-5627for Escherichia coli JM109 (MBC1L24), respectively.

(5) Determination of CDR of Mouse Monoclonal Antibody #23-57-137-1Against Human PTHrP.

The general structures of the H chain V region and the L chain V regionare similar to each other. That is, both structures have four frameworkregions ligated through three hypervariable regions [i.e.,complementarity determining regions (CDRs)]. The amino acid sequences ofthe framework regions are relatively well conserved, while the aminoacid sequences of the CDR regions exhibit an extremely high mutagenicity(Kabat, E. A. et al., “Sequence of Proteins of Immunological Interest”,US Dept. Health and Human Services, 1983).

On the basis of the above-mentioned facts, the CDRs were determined bysearching the homology of amino acid sequences of the mouse monoclonalantibody V region by reference to the Date Base of amino acid sequencesfor antibodies established by Kabat et al.

The amino acid sequences of CDRs 1-3 in the L chain V region are shownin SEQ ID Nos: 59-61, respectively, and the amino acid sequences of DCRs1-3 in the H chain V region are shown in SEQ ID Nos: 62-64,respectively.

TABLE 2 V region SEQ ID NO. CDR1 CDR2 CDR3 H chain V region 57 31-3550-66 99-107 L chain V region 65 23-34 50-60 93-105

Example 2 Construction of Chimeric Antibody

(1) Construction of Chimeric Antibody H Chain

(i) Construction of H Chain V Region

The cloned cDNA coding for mouse H chain V region was modified by a PCRmethod to ligate it to an expression vector carrying the genomic DNA forthe human H chain C region Cγ1. The downstream-side primer MBC1-S1 (SEQID NO: 7) used was designed so as to be hybridizable to the DNA codingfor the 5′-end region of the leader sequence of the V region and to haveboth a Kozak consensus sequence (Kozak, M. et al., J. Mol. Biol., 196,947-950, 1987) and a HindIII-recognition sequence. The upstream-sideprimer, MBC1-a (SEQ ID NO: 8), used was designed so as to behybridizable to the DNA coding for the 3′-end region of the J region andto have both a splice donor sequence and a BamHI-recognition sequence.The PCR reaction was conducted using TaKaRa Ex Taq (Takara Shuzo) and abuffer appended thereto. The PCR solution (50 μl) used comprised 0.07 μgof plasmid MBC1H04 as a template DNA, 50 pmoles of MBC1-a and 50 pmolesof MBC1-S1 as primers, 2.5U of TaKaRa Ex Taq and 0.25 mM dNTP in thebuffer, over which 50 μl of mineral oil was layered. Thirty cycles ofthe PCR reaction was conducted using a temperature cycle of 94° C. for 1min.; 55° C. for 1 min.; 72° C. for 2 min. The DNA fragments thusamplified by the PCR reaction were separated by agarose gelelectrophoresis using 3% Nu Sieve GTG Agarose (FMC Bio. Products).

Then, an agarose gel fragment containing a DNA fragment of 437 bp inlength was excised and the DNA fragment was purified therefrom usingGENECLEAN II Kit (BIO101) in accordance with an instruction included inthe kit. The purified DNA was collected by ethanol precipitation, andthen dissolved in 20 μl of a solution comprising 10 mM Tris-HCl (pH 7.4)and 1 mM EDTA. One μl of the resultant DNA solution was digested withrestriction enzymes BamHI and HindIII (Takara Shuzo) at 37° C. for 1hour. The digestion mixture was extracted with phenol and chloroform andthen precipitated with ethanol to collect a DNA.

The obtained HindIII-BamHI DNA fragment, which contains a DNA cordingfor the mouse H chain V region, was subcloned into pUC19 vector whichhad been digested with HindIII and BamHI. The resultant plasmid wassequenced by DNA Sequencer 373A (Perkin-Elmer) using M13 Primer M4 andM13 Primer RV as primers, and Dye Terminator Cycle Sequencing Kit(Perkin-Elmer). The plasmid contained a DNA of correct base sequencecoding for the mouse H chain V region derived from hybridoma#23-57-137-1 and had a HindIII-recognition sequence and a Kozak sequenceon its 5′-end region and a BamHI-recognition sequence on its 3′-endregion was designated “MBC1H/pUC19”.

(ii) Construction of H Chain V Region to be Used for the Preparation ofcDNA-Type of Mouse-Human Chimeric H Chain

The DNA coding for the mouse H chain V region constructed in the abovestep was modified by a PCR method to ligate it to a cDNA for the human Hchain C region Cγ1. The backward primer, MBC1HVS2, (SEQ ID NO: 9) usedfor the modification of H chain V region was designed so as to replacethe second amino acid (i.e., asparagine) of the sequence coding for thefront portion of the leader sequence of the V region with glycine and tohave a Kozak consensus sequence (Kozak, M. et al., J. Mol. Biol., 196,947-950, 1987) and the HindIII- and EcoRI-recognition sequences. Theforward primer MBC1HVR2 (SEQ ID NO: 10) used for the modification of Hchain V region was designed so as to be hybridizable to the DNA sequencecoding for the 3′-end region of the J region, to coding for the 5′-endregion of the C region and to have ApaI- and SmaI-recognition sequences.

The PCR reaction was conducted using TaKaRa Ex Taq (Takara Shuzo) and abuffer appended thereto. The PCR solution (50 μl) used comprised 0.6 μgof plasmid MBC1H/pUC19 as a template DNA, 50 pmoles of MBC1HVS2 and 50pmoles of MBC1HVR2 as primers, 2.5U of TaKaRa Ex Taq and 0.25 mM of dNTPin the buffer, over which 50 μl of mineral oil was layered. Thirtycycles of the PCR reaction was conducted using a temperature cycle of94° C. for 1 min.; 55° C. for 1 min.; 72° C. for 1 min. The DNAfragments amplified by the PCR reaction were separated by agarose gelelectrophoresis using 1% Sea Kem GTG Agarose (FMC Bio. Products) Then,an agarose gel fragment containing a DNA fragment of 456 bp in lengthwas excised and the DNA fragment was purified therefrom using GENECLEANII Kit (BIO101) in accordance with the procedure by the manufacturer.The purified DNA fragments were precipitated with ethanol and thendissolved in 20 μl of a solution comprising 10 mM Tris-HCl (pH 7.4) and1 mM EDTA.

One μl of the resultant DNA solution was digested with restrictionenzymes EcoRI and SmaI (Takara Shuzo) at 37° C. for 1 hour. Thedigestion mixture solution was extracted with phenol and chloroform andthen precipitated with ethanol to collect the DNA. The obtainedEcoRI-SmaI DNA fragments, which contains a DNA coding for the mouse Hchain V region, was subcloned into pUC19 vector which had been preparedby digesting the plasmid with EcoRI and SmaI. The resultant plasmid wassequenced by DNA Sequencer 373A (Perkin-Elmer) using M13 Primer M4 andM13 Primer RV as primers, and Dye Terminator Cycle Sequencing Kit(Perkin-Elmer). The plasmid which contained a DNA of correct basesequence coding for the mouse H chain V region derived from hybridoma#23-57-137-1 and had a HindIII-recognition sequence and a Kozak sequenceon its 5′-end region and ApaI- and SmaI-recognition sequences on its3′-end region was designated “MBC1Hv/pUC19”.

(iii) Construction of Expression Vector for Chimeric Antibody H Chain

cDNA containing human antibody H chain C region Cγ1 was prepared asfollows.

mRNA was prepared from a CHO cell into which both an expression vectorDHFR-ΔE-RVh-PM-1-f (see WO92/19759) coding for the genomic DNAs of thehumanized PM1 antibody H chain V region and the human antibody H chain Cregion IgG1 and an expression vector RV1-PM1a (see WO92/19759) codingfor the genomic DNAs of the humanized PM1 antibody L chain V region andthe human antibody L chain κ chain C region had been introduced. Usingthe mRNA obtained, was cloned a cDNA containing the humanized PM1antibody H chain V region and the human antibody C region Cγ1 by aRT-PCR method, and then subcloned into plasmid pUC19 on theHindIII-BamHI site. The plasmid subcloned was determined for its DNAsequence and the plasmid which had a correct base sequence wasdesignated “pRVh-PM1f-cDNA”.

Expression vector DHFR-ΔE-RVh-PM-1-f which had deletions of in theHindIII site between SV40 promoter and DHFR gene and the EcoRI sitebetween EF-1α promoter and the humanized PM1 antibody H chain V regionwas prepared for the construction of an expression vector for cDNAcontaining the humanized PM1 antibody H chain V region and the humanantibody C region Cγ1.

The plasmid pRVh-PM1f-cDNA obtained was digested with BamHI, blunt-endedwith Klenow fragment, and further digested with HindIII, to therebyobtain a blunt-ended HindIII-BamHI fragment. This blunt-endedHindIII-BamHI fragment was ligated to the above-mentioned HindIII site-and EcoRI site-deleted expression vector DHFR-ΔE-RVh-PM1-f which hadbeen digested with HindIII and BamHI to construct expression vectorRVh-PM1f-cDNA containing cDNAs coding for the humanized PM1 antibody Hchain V region and the human antibody C region Cγ1, respectively.

The expression vector RVh-PM1f-cDNA containing cDNAs coding for thehumanized PM1 antibody H chain V region and the human antibody C regionCγ1 was digested with ApaI and BamHI, and the DNA fragment containingthe H chain C region was collected therefrom. The resultant DNA fragmentwas introduced into the above-mentioned plasmid-MBC1Hv/pUC19, which hadbeen digested with ApaI and BamHI. The plasmid thus prepared wasdesignated “MBC1HcDNA/pUC19”. This plasmid is a plasmid contained cDNAscoding for the mouse antibody H chain V region and the human antibody Cregion Cγ1, respectively, and having EcoRI— and HindIII-recognitionsequences on its 5′-end and a BamHI-recognition sequence on its 3′-end.

The plasmid MBC1HcDNA/pUC19 was digested with EcoRI and BamHI to obtaina DNA coding for the chimeric antibody H chain. The resultant DNAfragment was introduced into expression vector pCOS1 which had beendigested with EcoRI and BamHI. The expression vector for the chimericantibody thus obtained was designated “MBC1HcDNA/pCOS1”. Here, theexpression vector pCOS1 was constructed using HEF-PMh-gγ1 (seeWO92/19759) by deleting therefrom the antibody gene by means of thedigestion with EcoRI and SmaI, and then ligating it to EcoRI-NotI-BamHIAdaptor (Takara Shuzo).

For preparing a plasmid for the expression in a CHO cell, the plasmidMBC1HcDNA/pUC19 was digested with EcoRI and BamHI to obtain a DNA codingfor the chimeric antibody H chain, which was then introduced intoexpression plasmid pCHO1 which had been digested with EcoRI and BamHI.The expression plasmid for the chimeric antibody thus obtained wasdesignated “MBC1HcDNA/pCHO1”. Here, the expression vector pCHO1 wasconstructed using DHFR-ΔE-rvH-PM1-f (see WO92/19759) by deletingtherefrom the antibody gene by means of the digestion with EcoRI andSmaI, and then ligating it to EcoRI-NotI-BamHI Adaptor (Takara Shuzo).

(2) Construction of Human L Chain C Region.

(i) Preparation of Cloning Vector

To construct pUC19 vector containing the human L chain C region, aHindIII site-deleted pUC19 vector was prepared. Two μg of pUC19 vectorwas digested in 20 μl of a reaction solution comprising 20 mM Tris-HCl(pH 8.5), 10 mM MgCl₂, 1 mM DTT, 100 mM KCl, 8 U of HindIII (TakaraShuzo) at 37° C. for 1 hour. The resultant digestion mixture solutionwas extracted with phenol and chloroform and then was subjected toethanol precipitation to collect the DNA of interest.

The DNA thus collected was reacted in 50 μl of a reaction solutioncomprising 50 mM Tris-HCl (pH 7.5), 10 mM MgCl₂, 1 mM DTT, 100 mM NaCl,0.5 mM dNTP and 6U of Klenow fragment (GIBCO BRL) at room temperaturefor 20 min. to thereby render the ends of the DNA blunt. This reactionmixture was extracted with phenol and chloroform and then subjected toethanol precipitation to collect the vector DNA.

The vector DNA thus collected was reacted in 10 μl of a reactionsolution comprising 50 mM Tris-HCl (pH 7.6), 10 mM MgCl₂, 1 mM ATP, 1 mMDTT, 5% (v/v) polyethylene glycol-8000 and 0.5 U of T4 DNA ligase (GIBCOBRL) at 16° C. for 2 hours to cause self-legation of the vector DNA. 5μl of the reaction solution was added to 100 μl of a solution containingcompetent cells of E. coli strain JM109 (Nippon Gene) and the resultantsolution was allowed to stand on ice for 30 min. at 42° C. for 1 min.and further on ice for 1 min. 500 ml of SOC culture medium was added tothe reaction solution, and then incubated at 37° C. for 1 hour. Theresultant solution was plated on a 2xYT agar medium (containing 50 μg/mlof ampicillin) which had been applied with X-gal and IPTG on its surface(Molecular Cloning: A Laboratory Manual, Sambrook, et al., Cold SpringHarbor Laboratory Press, 1989), and then cultured at 37° C. overnight,thereby obtaining a transformant.

The transformant was cultured on a 2xYT medium containing 50 μg/ml ofampicillin at 37° C. overnight. From the cell fraction of the culturemedium, was purified a plasmid DNA using Plasmid Mini Kit (QIAGEN) inaccordance with an instruction included in the kit. The purified plasmidwas digested with HindIII. The plasmid which was confirmed to have aHindIII site-deletion was designated “pUC19 ΔHindIII”.

(ii) Construction of DNA Coding for Human L Chain λ Chain C Region

The human antibody L chain λ chain C region has been known to have atleast four isotypes including Mcg⁺Ke⁺Oz⁻, Mcg⁻Ke⁻Oz⁻, Mcg⁻Ke^(−Oz) ⁺ andMcg⁻Ke⁺Oz⁻ (P. Dariavach., et al., Proc. Natl. Acad. Sci. USA, 84,9074-9078, 1987). The search was made for a human antibody L chain λchain C region homologous to the #23-57-137-1 mouse L chain λ chain Cregion based on the EMBL data base. As a result, it was found that theisotype Mcg⁺Ke⁺Oz⁻ (Accession No. X57819) (P. Dariavach, et al., Proc.Natl. Acad. Sci. USA, 84, 9074-9078, 1987) of the human antibody L chainλ chain exhibited the highest homology with the #23-57-137-1 mouse Lchain λ chain C region and showed 64.4% homology in terms of amino acidsequence and 73.4% homology in terms of DNA sequence.

Then the construction of the DNA coding for the human antibody L chain λchain C region was conducted by a PCR method. Each of the followingprimers used was synthesized using 394 DNA/RNA Synthesizer (ABI). Theprimers synthesized were HLAMB1 (SEQ ID NO: 11) and HLAMB3 (SEQ ID NO:13) both having a sense DNA sequence and HLAMB2 (SEQ ID NO: 12) andHLAMB4 (SEQ ID NO: 14) both having an antisense DNA sequence, eachprimer containing a complementary sequence of 20-23 bp in length on theboth ends.

External primers HLAMBS (SEQ ID NO: 15) and HLAMBR (SEQ ID NO: 16) havea sequence complementary to the primers HLAMB1 and HLAMB4, respectively,and contain the EcoRI-, HindIII- and BlnI-recognition sequences and theEcoRI-recognition sequence, respectively. In the first PCR reaction, theHLAMB1-HLAMB2 and HLAMB3-HLAMB4 reactions were conducted. After thereactions were completed, both of the resultants were mixed with eachother in equivalent quantities, and then assembled in the second PCRreaction. To the resultant reactant, were added the external primersHLAMBS and HLAMBR. This reaction mixture was subjected to the third PCRreaction for amplifying the full length DNA.

The PCR reactions were conducted using TaKaRa Ex Taq (Takara Shuzo) inaccordance with the procedure by the manufacturer. In the first PCRreaction, was used 100 μl of either a reaction solution comprising 5pmoles of HLAMB1, 0.5 pmole of HLAMB2 and 5U of TaKaRa Ex Taq (TakaraShuzo) or a reaction solution comprising 0.5 pmole of HLAMB3, 5 pmolesof HLAMB4 and 5U of TaKaRa Ex Taq (Takara Shuzo), over which 50 μl ofmineral oil was layered, and five cycles of the PCR reaction wasconducted using a temperature cycle program of 94° C. for 1 min., 60° C.for 1 min. and −72° C. for 1 min. In the second PCR reaction, was used amixture of 50 μl of each of the reaction solutions, over which 50 μl ofmineral oil was layered, and three cycles of the PCR reaction wasconducted using a temperature cycle program of 94° C. for 1 min., 60° C.for 1 min. and 72° C. for 1 min. In the third PCR reaction, the reactionsolution to which 50 pmoles of each of the external primers HLAMBS andHLAMBR were added was used, and thirty cycles of the PCR reaction wasconducted using a temperature cycle program of 94° C. for 1 min., 60° C.for 1 min. and 72° C. for 1 min.

The DNA fragment obtained by the third PCR reaction was subjected toelectrophoresis using 3% low melting agarose gel (NuSieve GTG Agarose,FMC), and collected and purified from the gel using GENECLEAN II Kit(BIO101) in accordance with the procedure included in the kit.

The DNA fragment thus obtained was digested in 20 μl of a reactionsolution comprising 50 mM Tris-HCl (pH 7.5), 10 mM MgCl₂, 1 mM DTT, 100mM NaCl and 8U of EcoRI (Takara Shuzo) at 37° C. for 1 hour. Thedigestion solution was extracted with phenol and chloroform and thenprecipitated with ethanol to thereby obtain the DNA. The DNA wascollected and dissolved in 8 μl of a solution comprising 10 mM Tris-HCl(pH 7.4) and 1 mM EDTA.

0.8 μg of the plasmid pUC19 ΔHindIII was digested with EcoRI in the samemanner as mentioned above. The digestion solution was extracted withphenol and chloroform, followed by ethanol precipitation, obtaining adigested plasmid pUC19 ΔHindIII. The digested plasmid thus obtained wasreacted in 50 μl of a reaction solution comprising 50 mM Tris-HCl (pH9.0), 1 mM MgCl₂ and alkaline phosphatase (E. coli C75; Takara Shuzo) at37° C. for 30 min. to dephosphorylate the plasmid (i.e., BAP-treatment).The reaction solution was subjected to phenol and chloroform extractionand ethanol precipitation to obtain the DNA. The DNA thus obtained wasdissolved in 10 μl of a solution comprising 10 mM Tris-HCl (pH 7.4) and1 mM EDTA.

One μl of the BAP-treated plasmid pUC19 ΔHindIII thus prepared was mixedwith 4 μl of the DNA obtained by the above-mentioned PCR reaction toligate to each other using DNA Ligation Kit Ver.2 (Takara Shuzo). Theresultant plasmid was introduced into a competent cell of E. coli,JM109, to form a transformant. The transformant was cultured overnightin 2 ml of a 2xYT medium containing 50 μg/ml of ampicillin. From thecell, the plasmid was purified using QIAprep Spin Plasmid Kit (QIAGEN).

With respect to the plasmid described above, the cloned DNA wasconfirmed on its sequence. For determination the DNA sequence, 373A DNASequencer (ABI) and primers “M13 Primer M4” and “M13 Primer RV” (TakaraShuzo) were used. As a result, it was found that the cloned DNA had adeleted portion of 12 bp in length therein. The plasmid containing theDNA was designated “cλΔ/pUC19”. Then, for making up for the portion,primers, HCLMS (SEQ ID NO: 17) and HCLMR (SEQ ID NO: 18), were newlysynthesized and a correct DNA was reconstructed by a PCR method.

The first PCR reaction was conducted, using the plasmid CλΔ/pUC19containing the deleted DNA as a template, and the primers HLAMBS andHCLMS or primers HCLMS and HLAMB4. Each of the PCR reaction products waspurified respectively. In the second PCR reaction, the PCR products wereassembled with each. To the resultant, were added external primersHLAMBS and HLAMB4, followed by the third PCR reaction for amplifying thefull length DNA.

In the first PCR reaction, 100 μl of a reaction solutions comprising 0.1μg CλΔ/pUC19 as a template, either 50 pmoles of each of the primersHLAMBS and HCLMR or 50 pmoles of each of the primers HCLMS and HLAMB4,and 5U of TaKaRa Ex Taq (Takara Shuzo) was used, over which 50 μl ofmineral oil was layered, and thirty cycles of the PCR reaction wasconducted using a temperature cycle of 94° C. for 1 min., 60° C. for 1min. and 72° C. for 1 min.

The PCR products, HLAMBS-HCLMR (236 bp) and HCLMS-HLAMB4 (147 bp), weresubjected to electrophoresis using 3% low melting agarose gel to isolatethe DNA fragment. The DNA fragment was then collected and purified fromthe gel using GENECLEAN II Kit (BIO101). In the second PCR reaction, 20μl of a reaction solution comprising 40 ng of the purified DNA fragmentsand 1U of TaKaRa Ex Taq (Takara Shuzo) were used, over which 25 μl ofmineral oil was layered, and five cycles of a temperature cycle of 94°C. for 1 min., 60° C. for 1 min. and 72° C. for 1 min. was executed.

In the third PCR reaction, 100 μl of a reaction solution comprising 2 μlof the reaction solution obtained by the second PCR reaction, 50 pmolesof each of external primers HLAMBS and HLAMB4 and 5U of TaKaRa Ex Taq(Takara Shuzo) were used, over which 50 μl of mineral oil was layered,and thirty cycles of the PCR reaction was conducted using a temperaturecycle of 94° C. for min., 60° C. for 1 min. and 72° C. for 1 min.,thereby obtaining a DNA fragment of 357 bp in length (third PCRproduct). The DNA fragment was subjected to electrophoresis using 3% lowmelting agarose gel to isolate the DNA fragment. The resultant DNAfragment was collected and purified using. GENECLEAN Kit (BIO101).

An amount of 0.1 μg of the DNA fragment thus obtained was digested withEcoRI, and then subcloned into a plasmid pUC19 ΔHindIII which had beentreated with BAP. The resultant plasmid was introduced into a competentcell of E. coli, JM109, to form a transformant. The transformant thusprepared was cultured overnight in 2 ml of a 2xYT medium containing 50μg/ml of ampicillin. From the cell fraction, the plasmid was purifiedusing QIAprep Spin Plasmid Kit (QIAGEN).

The DNA sequence of the plasmid thus obtained was confirmed by using M13Primer M4 and M13 Primer RV (Takara Shuzo) and determined 373A DNASequencer (ABI). The plasmid confirmed to have the correct DNA sequencewithout any deletion was designated “Cλ/pUC19”.

(iii) Construction of DNA Coding for Human L Chain, κ Chain C region

A DNA fragment coding for the L chain κ chain C region was cloned fromplasmid HEF-PM1k-gk (WO92/19759) by a PCR method. The forward primerHKAPS (SEQ ID NO: 19) was designed so as to contain the EcoRI- andHindIII and BlnI-recognition sequences and the backward primer HKAPA(SEQ ID NO: 20) was designed so as to contain the EcoRI-recognitionsequence, and both of them were synthesized using 394 DNA/RNASynthesizer (ABI).

A PCR reaction was conducted using 100 μl of a reaction solutioncomprising 0.1 μg of plasmid HEF-PM1k-gk as a template, 50 pmoles ofeach of primers HKAPS and HKAPA and 5U of TaKaRa Ex Taq (Takara Shuzo),over which 50 μl of mineral oil was layered. Thirty cycles of the PCRreaction was conducted using a temperature cycle of 94° C. for 1 min.,60° C. for 1 min. and 72° C. for 1 min., thereby obtaining a DNAfragment of 360 bp in length. The DNA fragment was isolated byelectrophoresis using 3% low melting agarose, and then collected andpurified using GENECLEAN II Kit (BIO101).

The DNA fragment thus obtained was digested with EcoRI and then clonedinto plasmid pUC19 ΔHindIII which had been treated with BAP. Theresultant plasmid was introduced into a competent cell of E. coli,JM109, to obtain a transformant. The transformant thus obtained wascultured overnight in 2 ml of 2xYT medium containing 50 μg/ml ofampicillin. From the cell fraction, the plasmid was purified usingQIAprep Spin Plasmid Kit (QIAGEN).

The purified plasmid DNA was sequenced using M13 Primer M4 and M13Primer RV (Takara Shuzo) by means of 373A DNA Sequencer (ABI). Theplasmid which was confirmed to have a correct base sequence wasdesignated “Cκ/pUC19”.

(3) Construction of Chimeric Antibody L Chain Expression Vector

Chimeric #23-57-137-1 antibody L chain expression vector wasconstructed. The DNA coding for #23-57-137-1 L chain V region wasligated to the HindIII and BlnI sites, present just front of the humanantibody C region, of each of the plasmid Cλ/pUC19 and Cκ/pUC19, therebyobtaining pUC19 vectors each containing DNA coding for the chimeric#23-57-137-1 antibody L chain V region and L chain λ or κ chain Cregion. Each of the resultant vectors was then digested with EcoRI toexcise the DNA coding for the chimeric antibody L chain and the DNA wassubcloned into HEF expression vector.

The DNA coding for #23-57-137-1 antibody L-chain V region was clonedfrom plasmid MBC1L24 by a PCR method. The primers were individuallysynthesized using 394 DNA/RNA Synthesizer (ABI). The backward primerMBCCHL1 used (SEQ ID NO: 21) was designed to contain aHindIII-recognition sequence and a Kozak sequence (Kozak, M. et al., J.Mol. Biol. 196, 947-950, 1987) and the forward primer MBCCHL3 (SEQ IDNO: 22) was designed to contain BglII- and RcoRI-recognition sequences.

The PCR reaction was conducted using 100 μl of a reaction solutioncomprising 10 mM Tris-HCl (pH 8.3), 50 mM KCl, 1.5 mM MgCl₂, 0.2 mMdNTP, 0.1 μg MBC1L24, 50 pmoles of each of primers MBCCHL1 and MBCCHL3as primers and 1 μl of AmpliTaq (PERKIN ELMER), over which 50 μl ofmineral oil was layered. Thirty cycles of the PCR reaction was conductedusing a temperature cycle of 94° C. for 45 sec., 60° C. for 45 sec. and72° C. for 2 min.

The DNA fragment of 444 bp was electrophoresed using 3% low meltingagarose gel, and collected and purified using GENECLEAN Kit (BIO101).The purified DNA fragment was dissolved in 20 μl of a solutioncontaining 10 mM Tris-HCl (pH 7.4) and 1 mM EDTA. One μl of the PCRproduct was digested in 20 μl of a reaction solution comprising 10 mMTris-HCl (pH 7.5), 10 mM MgCl₂, 1 mM DTT, 50 mM NaCl, 8U of HindIII(Takara Shuzo) and 8U of EcoRI (Takara Shuzo) at 37° C. for 1 hour. Thedigestion solution was extracted with phenol and chloroform, followed byethanol precipitation to collect the DNA as precipitates. The DNA thusobtained was dissolved in 8 μl of a solution comprising 10 mM Tris-HCl(pH 7.4) and 1 mM EDTA.

One μg of plasmid pUC19 was digested with HindIII and EcoRI in the samemanner as mentioned above, and then extracted with phenol andchloroform, followed by ethanol precipitation to collect the digestedplasmid. The resultant was treated with BAP [i.e., an alkalinephosphatase (E. coli C75; Takara Shuzo)]and then extracted with phenoland chloroform, followed by ethanol precipitation, thereby obtain theDNA. The resultant DNA was dissolved in 10 μl of a solution comprising10 mM Tris-HCl (pH 7.4) and 1 mM EDTA.

One μl of the BAP treated plasmid pUC19 was mixed with 4 μl of theabove-mentioned PCR product to ligate each other using DNA Ligation KitVer. 2 (Takara Shuzo). The resultant plasmid was introduced into acompetent cell of E. coli, JM109 (Nippon Gene), in the same manner asdescribed above to form a transformant. The transformant was inoculatedovernight on a 2xYT agar medium containing 50 μg/ml of ampicillin at 37°C. The resultant transformant was then cultured overnight in 2 ml of a2xYT medium containing 50 μg/ml of ampicillin at 37° C. From the cellfraction, the plasmid was purified using QIAprep Spin Plasmid Kit(QIAGEN). After determining the DNA sequence, the plasmid confirming tohave a correct DNA sequence was designated “CHL/pUC19”.

One μg of each of plasmids Cλ/pUC19 and Cκ/pUC19 was respectivelydigested in 20 μl of a reaction solution comprising 20 mM Tris-HCl (pH8.5), 10 mM MgCl₂, 1 mM DTT, 100 mM KCl, 8U of HindIII (Takara Shuzo)and 2U of BlnI (Takara Shuzo) at 37° C. for 1 hour. The digestionsolution was extracted with phenol and chloroform, followed by ethanolprecipitation, thereby obtaining a DNA. The DNA was treated with BAP at37° C. for 30 min. and then extracted with phenol and chloroform,followed by ethanol precipitation. The resultant was dissolved in 10 μlof a solution comprising 10 mM Tris-HCl (pH 7.4) and 0.1 mM EDTA.

Eight μg of the plasmid CHL/pUC19 which contained a DNA coding for#23-57-137-1 L chain V region was digested with HindIII and BlnI in thesame manner as mentioned above. The DNA fragment of 409 bp in lengththus obtained was electrophoresed using 3% low melting agarose gel andthen collected and purified using GENECLEAN II Kit (BIO101) from thegel. The DNA fragment was dissolved in 10 μl of a solution comprising 10mM Tris-HCl (pH 7.4) and 1 mM EDTA.

Four μl of the L chain V region DNA was subcloned into 1 μl of each ofthe BAP-treated plasmids Cλ/pUC19 or Cκ/pUC19, and then introduced intoa competent cell of E. coli, JM109, to form a transformant. Thetransformant was cultured overnight in 3 ml of a 2xYT medium containing50 μg/ml of ampicillin. From the cell fraction, the plasmid was isolatedand purified using QIAprep Spin Plasmid Kit (QIAGEN). The plasmids thusprepared were designated “MBC1L(λ)/pUC19” and “MBC1L(κ)/pUC19”,respectively.

Each of plasmids MBC1L(λ)/pUC19 and MBC1L(κ)/pUC19 was digested withEcoRI and then subjected to electrophoresis using 3% low melting agarosegel. A DNA fragment of 743 bp in length was isolated and purified fromthe gel using GENECLEANII Kit (BIO101) and dissolved in 10 μl of asolution comprising 10 mM Tris-HCl (pH 7.4) and 1 mM EDTA.

An amount of 2.7 μg of expression vector, plasmid HEF-PM1k-gk, wasdigested with EcoRI and then extracted with phenol and chloroform,followed by ethanol precipitation, thereby obtaining a DNA fragment. TheDNA fragment was treated with BAP, and then subjected to electrophoresisusing 1% low melting agarose gel. From the gel, a DNA fragment of 6561bp in length was isolated and purified therefrom using GENECLEANII Kit(BIO101). The DNA fragment was dissolved in 10 μl of a solutioncomprising 10 mM Tris-HCl (pH 7.4) and 1 mM EDTA.

The HEF vector thus prepared was treated with BAP, and 2 μl of theBAP-treated HEF vector was mixed with 3 μl of the EcoRI fragments ofplasmids MBC1L(λ)/pUC19 or MBC1L(κ)/pUC19, to ligate to each other. Theligation product was introduced into a competent cell of E. coli, JM109,to form a transformant. The transformant was cultured in 2 ml of a 2xYTmedium containing 50 μg/ml of ampicillin. From the cell fraction, theplasmid was purified using QIAprep Spin Plasmid Kit (QIAGEN).

The plasmid DNA thus purified was digested in 20 μl of a reactionsolution comprising 20 mM Tris-HCl (pH 8.5), 10 mM MgCl₂, 1 mM DTT, 100mM KCl, 8U of HindIII (Takara Shuzo) and 2 U of PvuI (Takara Shuzo) at37° C. for 1 hour. In this digestion reaction, it was assumed that ifthe above-mentioned DNA fragment was inserted into the vector in thecorrect orientation, a digestion fragment of 5104/2195 bp would beobtained, whereas if the above-mentioned DNA fragment was inserted intothe vector in the reverse orientation, a digestion fragment of 4387/2926bp would be obtained. Based on this assumption, the plasmids in whichthe fragment was inserted in a correct orientation were designated“MBC1L(λ)/neo” and “MBC1L(κ)/neo”, respectively.

(4) Transfection of COS-7 Cells

The expression plasmids prepared above were each expressed transientlyusing COS-7 cells in order to evaluate the chimeric antibody on itsbinding with and neutralizing activities against antigen.

The transient expression of the chimeric antibody was conducted using acombination of either plasmids MBC1HcDNA/pCOS1 and MBC1L(λ)/neo orplasmids MBC1HcDNA/pCOS1 and MBC1L(κ)/neo by means of electroporationusing Gene Pulser (Bio Rad) to co-transfect each of these plasmid DNAcombinations into COS-7 cells. That is, into 0.8 ml of a cell suspensionin which COS-7 cells were suspended in PBS(−) in a concentration of1×10⁷ cells/ml, 10 μg of each of the plasmid DNAs was added. Theresultant solution was applied with pulses at an electrostatic capacityof 1,500V and 2 μF to cause electroporation. After 10 min. of recoveryperiod at room temperature, the cells were suspended in a DMEM mediumcontaining 2% Ultra Low IgG fetal calf serum (GIBCO) and then culturedusing a 10 cm culture dish in a CO₂ incubator. After culturing for 72hours, a culture supernatant was collected and centrifuged to removecell debris and was provided as a sample for the ELISA assay.

In this procedure, the purification of the chimeric antibodies from theculture supernatant of COS-7 cells was conducted using AffiGel Protein AMAPSII Kit (Bio Rad) in accordance with an instruction included in kit.

(5) ELISA Assay

(i) Determination of Antibody Concentration

An ELISA plate for determining antibody concentration was prepared asfollows. Each of the wells of a 96-well plate for ELISA (Maxisorp, NUNC)was coated with 100 μl of a solution comprising goat anti-human IgGantibody (TAGO) prepared in a coating buffer (0.1 M NaHCO₃, 0.02% NaN₃)of a concentration of 1 μg/ml and then blocked with 200 μl of a dilutionbuffer [50 mM Tris-HCl, 1 mM MgCl₂, 0.1 M NaCl, 0.05% Tween20, 0.02%NaN₃, 1% bovine serum albumin (BSA); pH 7.2]. Into each well was added,a culture supernatant of the COS-7 cells in which the chimericantibodies had been expressed or the purified chimeric antibodies atstepwise dilution. After incubating at room temperature for 1 hour andwashing with PBS-Tween20, each well was added with 100 μl of a solutionof alkaline phosphatase-conjugated goat anti-human IgG antibodies(TAGO). After incubating at room temperature for 1 hour and washing withPBS-Tween20, each well was added with 1 mg/ml of a substrate solution(“Sigma104”, p-nitrophenylphosphoric acid, SIGMA). The solution wasmeasured for absorbance at 405 nm using Microplate Reader (Bio Rad). Asa standard for this determination, Hu IgG1λ Purified (The Binding Site)was used.

(ii) Determination of Antigen Binding Ability

An ELISA plate for the determination of antigen binding ability wasprepared as follows. Each of the wells of a 96-well plate for ELISA wascoated with 100 μl of a solution comprising human PTHrP (1-34) (PeptideResearch Institute) prepared in a coating buffer of a concentration of 1μg/ml and then blocked with 200 μl of a dilution buffer. Into each wellwas added, the culture supernatant of the COS-7 cells in which thechimeric antibodies had been expressed or the purified chimericantibodies at stepwise dilution. After incubating at room temperatureand washing with PBS-Tween20, each well was added with 100 μl of asolution of alkaline phosphatase-conjugated goat anti-human IgGantibodies (TAGO). After incubating at room temperature and washing withPBS-Tween20, each well was added with 1 mg/ml of a substrate solution(“Sigma104”, p-nitrophenylphosphoric acid, SIGMA). The solution wasmeasured for absorbance at 405 nm using Microplate Reader (Bio Rad).

As a result, it was found that the chimeric antibody had a bindingability against human PTHrP (1-34) and also had a correct structure ofthe cloned mouse antibody V region (FIG. 4). It was also found thatthere was no difference in the binding ability against PTHrP (1-34)between the chimeric antibody in which the L chain C region has λ chainand those in which the L chain C region has κ chain. Therefore, the Lchain C region of the humanized antibody was constructed using thehumanized antibody L chain λ chain.

(6) Establishment of CHO Stable Transformed Cell Line

For establishing a stable transformant for the chimeric antibody, theabove-mentioned expression plasmid was introduced into a CHO cell(DXB11).

Establishment of a stable transformant for the chimeric antibody wasconducted using combinations of expression plasmids for CHO cell,MBC1HcDNA/pCHO1 and MBC1L(λ)/neo or expression plasmids for CHO cell,MBC1HcDNA/pCHO1 and MBC1L(κ)/neo. These combinations of plasmids wereindividually co-transfected into CHO cells by electroporation using GenePulser (Bio Rad). Each of the expression vectors was cleaved withrestriction enzyme PvuI to obtain a lenear DNA. The resultant DNA wascollected by extraction with phenol and chloroform and subsequentprecipitation with ethanol. The plasmid DNAs thus prepared wererespectively subjected to electroporation. Ten μg of each of the plasmidDNAs was added to 0.8 ml of a cell suspension containing CHO cells inPBS(−) in a concentration of 1×10⁷ cells/ml. The resultant mixture wasapplied with pulses at an electrostatic capacity of 1,500V and 25 μF.After 10 min. of recovery period at room temperature, the electroporatedcells were suspended in a MEM-α medium (GIBCO) supplemented with 10%fetal calf serum (GIBCO). The resultant suspension was cultured usingthree 96-well plates (Falcon) in a CO₂ incubator. On the day afterstarting the cultivation, the medium was replaced by a selective medium[a MEM-α medium supplemented with 10% fetal calf serum (GIBCO) and 500mg/ml of GENETICIN (G418Sulfate; GIBCO) without ribonucleoside ordeoxyribonucleoside]. From the culture medium, cells into which theantibody gene was introduced were selected. After replacing theselective medium by a fresh one, before and after two weeks ofcultivation, the cells were observed under a microscope. When a cellgrowth was observed, the cells were determined for the amount ofantibodies produced by the above-mentioned ELISA assay. Among the cells,those which produced a larger amount of antibodies were selectivelycollected.

The scale up of the culture of the stable transformant for theestablished antibodies was conducted in a roller bottle using a MEMmedium supplemented with 2% Ultra Low IgG fetal calf serum withoutribonucleoside or deoxyribonucleoside. On day 3 and day 4 of thecultivation, the culture supernatant was collected and then filteredusing a filter having a pore size of 0.2 μm (Millipore) to remove celldebris therefrom.

Subsequently, the purification of the chimeric antibodies from theculture supernatant of the CHO cells was conducted using POROS Protein AColumn (PerSeptive Biosystems) on ConSep LC100 (Millipore) in accordancewith an instruction included within. The purified chimeric antibodieswere provided as samples for the determination of neutralizing activityand for the examination of efficacy on hypercalcemic model animals. Theconcentration and the binding activity of the purified chimericantibodies against antigen were determined by the same ELISA system.

Example 3 Construction of Humanized Antibody

(1) Construction of Humanized Antibody H Chain

(i) Construction of Humanized H Chain V Region

Humanized #23-57-137-1 antibody H chain was prepared by CDR-graftingtechnique by means of PCR method. For preparing a humanized #23-57-137-1antibody H chain (version “a”) having a FR derived from human antibodyS31679 (NMRF-PDB; Cuisinier, A. M. et al., Eur. J. Immunol., 23,110-118, 1993), the following six types of PCR primers were used:CDR-grafting primers: MBC1HGP1 (SEQ ID NO: 23) and MBC1HGP3 (SEQ ID NO:24) (both containing a sense DNA sequence) and MBC1HGP2 (SEQ ID NO: 25)and MBC1HGP4 (SEQ ID NO: 26) (both containing an antisense DNAsequence), all of which containing a complementary sequence of 15-21 bpin length on both ends thereof; and external primers: MBC1HVS1 (SEQ IDNO: 27) and MBC1HVR1 (SEQ ID NO: 28), both having a homology with theCDR-grafting primers MBC1HGP1 and MBC1HGP4, respectively.

The CDR-grafting primers MBC1HGP1, MBC1HGP2, MBC1HGP3 and MBC1HGP4 wereisolated using an urea-denatured polyacrylamide gel (Molecular Cloning:A Laboratory Manual, Sambrook, et al., Cold Spring Harbor LaboratoryPress, 1989) and extracted from the gel fraction by a crush-and-soakmethod (Molecular Cloning: A Laboratory Manual, Sambrook, et al., ColdSpring Harbor Laboratory Press, 1989) in the following manner.

One nmole of each of the CDR-grafting primers was isolated with 6%denatured polyacrylamide gel to obtain DNA fragments. From the resultantDNA fragments, those having a desired length was identified on a silicagel thin plate by irradiation of UV ray and then collected therefrom bya crush-and-soak method. The resultant was dissolved in 20 μl of asolution comprising 10 mM Tris-HCl (pH 7.4) and 1 mM EDTA. The PCRreaction was conducted using TaKaRa Ex Taq (Takara Shuzo). The reactionsolution (100 μl) used in the PCR reaction comprised 1 μl of each of theabove-mentioned CDR-grafting primers MBC1HGP1, MBC1HGP2, MBC1HGP3 andMBC1HGP4, 0.25 mM dNTP and 2.5U of TaKaRa Ex Taq in the buffer. Fivecycles of the PCR reaction was conducted using a temperature cycle of94° C. for 1 min., 55° C. for 1 min. and 72° C. for 1 min. Into theresultant reaction mixture were added, both of the external primersMBC1HVS1 and MBC1HVR1 each in an amount of 50 pmoles. Using thisreaction mixture, additional 30 cycles of the PCR reaction was conductedusing the same temperature cycle. The DNA fragment thus amplified wasisolated by agarose gel electrophoresis using 4% Nu Sieve GTG agarose(FMC Bio. Products).

An agarose fragment containing a DNA fragment of 421 bp in length wasexcised and the DNA fragment was purified therefrom using GENECLEANIIKit (BIO101) in accordance with an instruction included in the kit. TheDNA fragment thus purified was precipitated with ethanol and thendissolved in 20 μl of a solution comprising 10 mM Tris-HCl (pH 7.4) and1 mM EDTA. The PCR reaction mixture obtained was used for subcloning ofthe DNA fragment into plasmid pUC19 which had been prepared by digestingthe plasmid with BamHI and HindIII; thereafter the base sequence of theresultant plasmid was determined. A plasmid having a correct sequencewas designated “hMBCHv/pUC19”.

(ii) Construction of H Chain V Region for Humanized H Chain cDNA

For the ligation to the cDNA of humanized H chain C region Cγ1, the DNAof the humanized H chain V region constructed in the above step wasmodified by a PCR method. In this method, the backward primer MBC1HVS2used was designed so as to be hybridizable to the sequence coding forthe 5′-end region of the leader sequence of the V region and to carry aKozak consensus sequence (Kozak et al., J. Mol. Biol. 196, 947-950,1987) and HindIII- and EcoRI-recognition sequences. The forward primerMBC1HVR2 used for the modification of the DNA for the H chain V regionwas designed so as to be hybridizable to both the DNA sequence codingfor the 3′-end region of the J region and the DNA sequence coding forthe 5′-end region of the C region and to carry ApaI- andSamI-recognition sequences.

The PCR reaction was conducted using TaKaRa Ex Taq (Takara Shuzo) and abuffer was used therewith. The reaction solution used for the PCRreaction comprised 0.4 μg of hMBCHv/pUC19 as a DNA template, 50 pmolesof each of MBC1HVS2 and MBC1HVR2 as primers, 2.5U of TaKaRa Ex Taq and0.25 mM dNTP in the buffer. Thirty cycles of the PCR reaction wasconducted using a temperature cycle of 94° C. for 1 min., 55° C. for 1min. and 72° C. for 1 min. The DNA fragment thus amplified by the PCRmethod was isolated by agarose gel electrophoresis using 3% Nu Sieve GTGagarose (FMC Bio. Products).

A DNA fragment of 456 bp in length was excised and the DNA fragment waspurified therefrom using GENECLEANII Kit (BIO101) in accordance with aninstruction included within. The DNA fragment thus purified wasprecipitated with ethanol and then dissolved in 20 μl of a solutioncomprising 10 mM Tris-HCl (pH 7.4) and 1 mM EDTA. The PCR reactionmixture thus obtained was used for subcloning of the DNA fragment intoplasmid pUC19 which had been prepared by digesting the plasmid withEcoRI and SmaI; thereafter the DNA sequence of the resultant plasmid wasdetermined. The plasmid DNA thus prepared which contains a DNA codingfor the mouse H chain V region derived from the hybridoma #23-57-137-1and also contains the EcoRI- and HindIII-recognition sequences and aKozak sequence on the 5′-end and the ApaI- and SmaI-recognitionsequences on the 3′-end was designated “hMBC1Hv/pUC19”.

(2) Construction of Expression Vector for Humanized Antibody H Chain

Plasmid RVh-PM1f-cDNA containing a cDNA sequence of hPM1 antibody Hchain was digested with ApaI and BamHI to obtain a DNA fragmentcontaining a base sequence of the H chain C region. The DNA fragment wasintroduced into plasmid hMBC1Hv/pUC19 which had been prepared bydigesting the plasmid with ApaI and BamHI. The plasmid thus prepared wasdesignated “hMBC1HcDNA/pUC19”. This plasmid was a plasmid containingboth a DNA coding for the humanized #23-57-137-1 antibody H chain Vregion and a DNA coding for the human H chain C region Cγ1 and to haveEcoRI- and HindIII-recognition sequences on the 5′-end region and aBamHI-recognition sequence on the 3′-end region. The base sequence andthe corresponding amino acid sequence of the humanized H chain version“a” contained in the plasmid hMBC1HcDNA/pUC19 are shown in SEQ ID NO: 58and SEQ ID NO: 56, respectively.

The plasmid hMBC1HcDNA/pUC19 was digested with EcoRI and BamHI to obtaina DNA fragment containing a base sequence coding for the H chain. TheDNA fragment was introduced into expression plasmid pCOS1 which had beenprepared by digesting the plasmid with EcoRI and BamHI. The expressionplasmid for a humanized antibody thus obtained was designated“hMBC1HcDNA/pCOS1”.

To prepare a plasmid for expression in a CHO cell, plasmidhMBC1HcDNA/pUC19 was digested with EcoRI and BamHI to obtain a DNAfragment containing a DNA coding for the H chain. The DNA fragment wasintroduced into expression vector pCHO1 which had been prepared bydigesting the plasmid with EcoRI and BamHI. The expression plasmid forthe humanized antibody thus obtained was designated “hMBC1HcDNA/pCHO1”.

(3) Construction of L Chain Hybrid Variable Region

(i) Preparation of FR1,2/FR3,4 Hybrid Antibody

A DNA coding for the L chain in which the FR regions were recombinedwith those from a humanized antibody and a mouse (chimeric) antibody wasconstructed and evaluated the regions on their suitability forhumanization. In this step, a hybrid antibody comprising FR1 and FR2both derived from a human antibody and FR3 and FR4 both derived from amouse antibody was prepared by utilizing the AflII restriction sitepresent in CDR 2.

Ten μg of each of plasmids MBC1L(λ)/neo and hMBC1L(λ)/neo was digestedin 100 μl of a reaction solution comprising 10 mM Tris-HCl (pH 7.5), 10mM MgCl₂, 1 mM DTT, 50 mM NaCl, 0.01% (w/v) of BSA and 10 U of AflII(Takara Shuzo) at 37° C. for 1 hour. The reaction solution was subjectedto electrophoresis using 2% low melting agarose gel, and DNA fragmentsof 6282 bp in length (referred to as “c1”) and 1022 bp in length(referred to as h1) were collected and purified from the gel usingGENECLEANII Kit (BIO101).

One μg of each of the c1 and h1 fragments obtained was subjected totreatment with BAP. The DNA fragment was extracted with phenol andethanol, collected by ethanol precipitation, dissolved in 10 μl of asolution comprising 10 mM Tris-HCl (pH 7.4) and 1 mM EDTA.

One μl of each of the BAP-treated c1 and h1 DNA fragments were mixedwith 4 μl of the h2 and c2 DNA fragments, respectively, to ligate toeach other (at 4° C. overnight). The ligation product was introducedinto a competent cell of E. coli, JM109, to form a transformant. Thetransformant was cultured in 2 ml of a 2xYT medium containing 50 μg/mlof ampicillin. From the cell fraction, the plasmid was purified usingQIAprep Spin Plasmid Kit (QIAGEN).

The plasmid DNA purified was digested in 20 μl of a reaction solutioncomprising 10 mM Tris-HCl (pH 7.5), 10 mM MgCl₂, 1 mM DTT, 2U of ApaLI(Takara Shuzo), and 8U of BamHI (Takara Shuzo) or HindIII (Takara Shuzo)at 37° C. for 1 hour. In this step, the plasmid was identified based onthe expectation that if the c1-h2 fragment was correctly ligated in theplasmid, this ligation would give an ApaLI-digestion fragment of5560/1246/498 bp or a BamHI/HindIII-digestion fragment of 7134/269 bp.

The expression vector coding for the human FR1,2/mouse FR3,4 hybridantibody L chain was designated “h/mMBC1L(λ)/neo”. On the other hand, aclone for the h1-c1 could not be obtained. Therefore, recombination on apUC vector was conducted, followed by cloning to a HEF vector. Here,used as templates were plasmid hMBC1Laλ/pUC19, which contained a DNAcoding for a humanized antibody L chain V region having no amino acidreplacements and plasmid hMBC1Ldλ/pUC19, which contained a DNA codingfor a humanized antibody L chain V region having an amino acidreplacement at the 91-position amino acid in FR3 (i.e., amino acidnumber 87 according to the definition by Kabat), of tyrosine, byisoleucine.

Ten μl of each of plasmids MBC1L(λ)/pUC19, hMBC1Laλ/pUC19 andhMBC1Ldλ/pUC19 was digested in 30 μl of a reaction solution comprising10 mM Tris-HCl (pH 7.5), 10 mM MgCl₂, 1 mM DTT, 50 mM NaCl, 0.01% (w/v)of BSA, 16U of HindIII and 4U of AflII at 37° C. for 1 hour. Thereaction solution was subjected to electrophoresis using 2% low meltingagarose gel, and then collected and purified the following DNA fragmentsusing GENECLEANII Kit (BIO101): a DNA fragment of 215 bp in length fromplasmid MBC1L(λ)/pUC19 (referred to as “c2′”) or a DNA fragment of 3218bp in length from each of plasmids hMBC1Laλ/pUC19 and hMBC1Ldλ/pUC19 MBC(referred to as “hal′” and “hdl′”, respectively).

Each of the hal′ and hdl′ fragments was individually ligated to thec2′-fragment and then introduced into a competent cell of E. coli,JM109, to form a transformant. The transformant was cultured in 2 ml ofa 2xYT medium containing 50 μg/ml of ampicillin. From the cell fraction,the plasmid was purified using QIAprep Spin Plasmid Kit (QIAGEN). Theresultant plasmid DNAs containing the hal′ fragment and the hdl′fragment were designated “m/hMBC1Laλ/pUC19” and “m/hMBC1Ldλ/pUC19”,respectively.

Each of the plasmids m/hMBC1Laλ/pUC19 and m/hMBC1Ldλ/pUC19 was digestedwith EcoRI. The DNA fragment of 743 bp in length was electrophoresedusing 2% low melting agarose gel, and then collected and purified fromthe gel using GENECLEANII Kit (BIO101). The resultant was dissolved in20 μl of a solution comprising 10 mM Tris-HCl (pH 7.4) and 1 mM EDTA.

Four μl of the DNA fragment obtained was mixed with 1 μl of theabove-mentioned BAP-treated HEF vector to ligate to each other. Theligation product was introduced into a competent cell of E. coli, JM109,to form a transformant. The transformant was cultured in 2 ml of a 2xYTmedium supplemented with 50 μg/ml of ampicillin. From the cell fraction,the plasmid DNA was purified using QIAprep Spin Plasmid Kit (QIAGEN).

The plasmid DNA purified was digested in 20 μl of a reaction solutioncomprising 20 mM Tris-HCl (pH 8.5), 10 mM MgCl₂₁ 1 mM DTT, 100 mM KCl,8U of HindIII (Takara Shuzo) and 2U of PvuI (Takara Shuzo) at 37° C. for1 hour. In this step, the plasmid DNA was identified based on theexpectation that if the DNA fragment was inserted in the plasmid in acorrect orientation, this digestion would give a digestion fragment of5104/2195 bp, whereas if the DNA fragment is inserted in the plasmid inthe reverse orientation, this digestion would give a digestion fragmentof 4378/2926 bp. The plasmids thus obtained were expression vectorscoding for mouse FR1,2/human FR3,4 hybrid antibody L-chai, which weredesignated expression vectors “m/hMBC1Laλ/neo” and “m/hMBC1Ldλ/neo”,respectively.

(ii) Preparation of FR1/FR2 Hybrid Antibody

An FR1/FR2 hybrid antibody was prepared in the same manner as mentionedabove using a SnaBI restriction site present in CDR1.

Ten μg of each of the plasmids MBC1L(λ)/neo and mMBC1L(λ)/neo wasdigested in 20 μl of a reaction solution comprising 10 mM Tris-HCl (pH7.9)., 10 mM MgCl₂, 1 mM DTT, 50 mM NaCl, 0.01% (w/v) of BSA and 6U ofSnaBI (Takara Shuzo) at 37° C. for 1 hour. The resultant reactionsolution was further digested in 50 μl of a reaction solution comprising20 mM Tris-HCl (pH 8.5), 10 mM MgCl₂, 1 mM DTT, 100 mM KCl, 0.01% (w/v)of BSA and 6U of PvuI at 37° C. for 1 hour.

The resultant reaction solution was subjected to electrophoresis using1.5% low melting agarose gel, and then DNA fragments of 4955 bp and 2349bp in length were collected and purified from the gel using GENECLEANIIKit (BIO101). The DNA fragments obtained from plasmid MBC1L(λ)/neo weredesignated “m1” (4955 bp) and “m2” (2349 bp) and the DNA fragmentsobtained from plasmid h/mMBC1L(λ)/neo were designated “hm1” (4955 bp)and “hm2” (2349 bp). Each of the DNA fragments obtained was dissolved in40 μl of a solution comprising 10 mM Tris-HCl (pH 7.4) and 1 mM EDTA.

One μl of each of the m1 and hm1 fragments was ligated to 4 μl of eachof the hm2 and m2 fragments, respectively, and then introduced into acompetent cell of E. coli, JM109, to form: a transformant. Thetransformant obtained was cultured in 2 ml of a 2xYT medium containing50 μg/ml of ampicillin. From the cell fraction, the plasmid DNA waspurified using QIAprep Spin Plasmid Kit QIAGEN).

The plasmid-DNA purified was digested in 20 μl of a reaction solutioncomprising 10 mM Tris-HCl (pH 7.5), 10 mM MgCl₂, 1 mM DTT and either 8Uof ApaI (Takara Shuzo) or 2U of ApalI (Takara Shuzo) at 37° C. for 1hour.

The plasmids (m1-hm2 and hm1-m2) thus prepared were identified based onthe expectation that if each of the DNA fragments is ligated in theplasmid in a correct orientation, the digestion of the plasmid (m1-hm2)with ApaI and ApaLI would give a fragment of 7304 bp and fragments of5560/1246/498 bp, respectively, and the digestion of the plasmid(hm1-m2) with ApaI and ApaLI would give fragments of 6538/766 bp and afragment of 3535/2025/1246/498 bp, respectively.

As expression vector coding for a human FR1/mouse FR2,3,4 hybridantibody L chain was designated “hmmMBC1L(λ)/neo” and a expressionvector cording for a mouse FR1/human FR2/mouse FR3,4 hybrid antibody Lchain was designated “mhmMBC1L(λ)/neo”.

(4) Construction of Humanized Antibody L Chain

A humanized #23-57-137-1 antibody L chain was prepared by CDR-graftingtechnique by means of PCR method. That is, a humanized #23-57-137-1antibody L chain (version “a”) was prepared which contained FR1, FR2 andFR3 drived from human antibody HSU03868 (GEN-BANK, Deftos M. et al.,Scand. J. Immunol., 39, 95-103, 1994) and FR4 drived from human antibodyS25755 (NBRF-PDB) using the six types of PCR primers:

CDR-grafting primers, MBC1LGP1 (SEQ ID NO: 29) and MBC1LGP3 (SEQ ID NO:30), both having a sense DNA sequence, CDR-grafting primers, MBC1LGP2(SEQ ID NO: 31) and MBC1LGP4 (SEQ ID NO: 32), both having an antisenseDNA sequence, all of which CDR-grafting primers having a complementarysequence of 15-21 bp on the both ends thereof; and external primers,MBC1LVS1 (SEQ ID NO: 33) and MBC1LVR1 (SEQ ID NO: 34), both having ahomology with the CDR-grafting primers MBC1LGP1 and MBC1LGP4,respectively.

The CDR-grafting primers MBC1LGP1, MBC1LGP2, MBC1LGP3 and MBC1LGP4 wereisolated using a urea-denatured polyacrylamide gel (Molecular Cloning: ALaboratory Manual, Sambrook et al., Cold Spring Harbor Laboratory Press,1989) and extracted from the gel fraction by a crush-and-soak method(Molecular Cloning: A Laboratory Manual, Sambrook et al., Cold SpringHarbor Laboratory Press, 1989).

One nmole of each of the CDR-grafting primers was isolated with 6%denatured polyacrylamide gel. From the resultant, a DNA fragment havinga desired length was identified on a silica gel thin plate byirradiation of UV ray and then collected therefrom by a crush-and-soakmethod. The resultant was dissolved in 20 μl of a solution comprising 10mM Tris-HCl (pH 7.4) and 1 mM EDTA.

The PCR reaction was conducted using TaKaRa Ex Taq (Takara Shuzo) with abuffer. The reaction solution (100 μl) used in the PCR reactioncomprised 1 μl of each of the CDR-grafting primers MBC1LGP1, MBC1LGP2,MBC1LGP3 and MBC1LGP4, 0.25 mM dNTP, 2.5U of TaKaRa Ex Taq in thebuffer. Five cycles of the PCR reaction was conducted using atemperature cycle of 94° C. for 1 min., 55° C. for 1 min. and 72° C. for1 min. Into the resultant reaction mixture were added 50 pmoles of eachof the external primers MBC1LVS1 and MBC1LVR1. Using this reactionmixture additional thirty cycles of the PCR reaction was conducted usingthe same temperature cycle. The DNA fragment thus amplified was isolatedby agarose gel electrophoresis using 3% Nu Sieve GTG agarose (FMC Bio.Products).

An agarose fragment containing a DNA fragment of 421 bp in length wasexcised and the DNA fragment was purified from the gel using GENECLEANIIKit (BIO101) in accordance with the instruction included with the kit.The PCR reaction mixture thus prepared was used for subcloning of theDNA fragment into plasmid pUC19 which had been prepared by digesting theplasmid with BamHI and HindIII. The resultant plasmid was determined ofits DNA sequence. The plasmid thus prepared was designated“hMBCL/pUC19”. In this plasmid, however, it was found that the104-position amino acid (amino acid number 96 according to thedetermining by Kabat) of CDR4 was replaced with arginine. To correctthis amino acid to tyrosine, primer MBC1LGP10R (SEQ ID NO: 35) wasdesigned and synthesized. Then the PCR reaction was conducted usingTaKaRa Ex Taq (Takara Shuzo) with a buffer. The reaction solution (100μl) used in the PCR reaction comprised 0.6 μg of the plasmid hMBCL/pUC19as a template DNA, 50 pmoles of each of the primers MBC1LVS1 andMBC1LGP10R, 2.5U of TaKaRa Ex Taq (Takara Shuzo) and 0.25 mM dNTP in thebuffer, over which mineral oil was layered. Thirty cycles of the PCRreaction was conducted using a temperature cycle of 94° C. for 1 min.,55° C. for 1 min. and 72° C. for 1 min. The DNA fragment thus amplifiedby PCR method was isolated by agarose gel electrophoresis using 3% NuSieve GTG agarose (FMC Bio. Products).

A DNA fragment of 421 bp in length was excised and the DNA fragment waspurified therefrom using GENECLEANII Kit (BIO101) in accordance with aninstruction included with the kit. The PCR reaction mixture thusprepared was used for subcloning of the DNA fragment into plasmid pUC19which had been prepared by digesting the plasmid with BamHI and HindIII.

The plasmid was determined of its DNA sequence using M13 Primer M4 andM13 Primer RV. As a result, it was confirmed that the plasmid had acorrect sequence. The plasmid was then digested with HindIII and BlnIand a DNA fragment of 416 bp was isolated therefrom by electrophoresisusing 1% agarose gel. The DNA fragment was purified using GENECLEANIIKit (BIO101) in accordance with an instruction included with the kit andthen introduced into plasmid Cλ/pUC which had been prepared by digestingthe plasmid with HindIII and BlnI. The resultant plasmid was designated“hMBC1Laλ/pUC19”. This plasmid was digested with EcoRI to obtain a DNAfragment coding for humanized L chain. The DNA fragment was introducedinto plasmid pCOS1 so that the initiation codon for the humanized Lchain was located downstream from the EF1α promoter. The plasmid thusobtained was designated “hMBC1Laλ/pCOS1”. The DNA sequence (includingthe corresponding amino acid sequence) of the humanized L chain version“a” is shown in SEQ ID NO: 66. The amino acid sequence of the version“a” is shown in SEQ ID NO: 47.

Version “b” was prepared using mutagenic introduction technique by a PCRmethod. The version “b” was designed so as to replace the 43-positionamino acid, glycine, (amino acid number 43 according to the definitionby Kabat) with proline and to replace the 49-position amino acid,lysine, (amino acid number 49 according to the definition by Kabat) withaspartic acid. The PCR reaction was conducted using plasmidhMBC1Laλ/pUC19 as a template with a mutagenic primer MBC1LGP5R (SEQ IDNO: 36) and primer MBC1LVS1. The DNA fragment obtained was digested withBamHI and HindIII, and the digestion fragment was subcloned into theBamHI-HindIII site of pUC19. After sequencing, the plasmid DNA obtainedwas digested with HindIII and AflII, and the resultant digestionfragment was ligated to plasmid hMBC1Laλ/pUC19 which had been preparedby digesting the plasmid with HindIII and AflII.

The plasmid thus obtained was designated “hMBC1Lbλ/pUC19”. This plasmidDNA was digested with EcoRI to obtain a DNA fragment containing a DNAcoding for the humanized L chain. The DNA fragment was introduced intoplasmid pCOS1 so that the initiation codon for the humanized L chain waslocated downstream from the EF1α promoter. The plasmid thus obtained wasdesignated “hMBC1Lbλ/pCOS1”.

Version “c” was prepared using mutagenic introduction technique by a PCRmethod. The version “c” was designed so as to replace the 84-positionamino acid, serine, (amino acid number 80 according to the definition byKabat) with proline. The PCR reaction was conducted using plasmidhMBC1Laλ/pUC19 as a template with a mutagenic primer MBC1LGP6S (SEQ IDNO: 37) and primer M13 Primer RV. The DNA fragment obtained was digestedwith BamHI and HindIII and then subcloned into pUC19 which had beenprepared by digesting the plasmid with BamHI and HindIII. Aftersequencing, the plasmid DNA obtained was digested with BstPI andAor51HI, and the resultant DNA fragment was ligated to plasmidhMBC1Laλ/pUC19 which had been prepared by digesting the plasmid withBstPI and Aor51HI. The plasmid thus obtained was designated“hMBC1Laλ/pUC19”. This plasmid DNA was digested with EcoRI to obtain asequence containing a sequence coding for the humanized L chain. Thesequence was introduced into the EcoRI site of plasmid pCOS1 so that theinitiation codon for the humanized L chain was located downstream fromthe EF1α promoter. The plasmid thus obtained was designated“hMBC1Lcλ/pCOS1”.

Versions “d”, “e” and “f” were also prepared using mutagenicintroduction technique by a PCR method. Each of the versions “d”, “e”and “f” was designed so as to replace the 91-position amino acid,tyrosine, (amino acid number 87 according to the definition by Kabat)with isoleucine in the versions “a”, “b” and “c”, respectively. For eachof the versions “d”, “e” and “f”, a PCR reaction was conducted usingeach of plasmid hMBC1Laλ/pCOS1 (for version “d”), hMBC1Lbλ/pCOS1 (forversion “e”) and hMBC1Lcλ/pCOS1 (for version “f”) as a template with amutagenic primer MBC1LGP11R (SEQ ID NO: 38) and primer M-S1 (SEQ ID NO:44). The DNA fragment thus obtained was digested with BamHI and HindIIIand then subcloned into pUC19 which had been prepared by digesting pUC19with BamHI and HindIII. After sequencing, the plasmid was digested withHindIII and BlnI, and the resultant digestion fragment was ligated toplasmid Cλ/pUC19 which had been prepared by digesting the plasmid withHindIII and BlnI.

The plasmids thus obtained were respectively designated“hMBC1Ldλ/pUC19”, “hMBC1Leλ/pUC19” and “hMBC1Lfλ/pUC19”. Each of theseplasmids was digested with EcoRI to obtain a DNA fragment containing aDNA coding for the humanized L chain. The DNA fragment was introducedinto the EcoRI site of plasmid pCOS1 so that the initiation codon forthe humanized L chain was located downstream from the EF1α promoter ofthe plasmid. The plasmids thus obtained were respectively designated“hMBC1Ldλ/pCOS1”, “hMBC1Leλ/pCOS1” and “hMBC1Lfλ/pCOS1”.

Versions “g” and “h” were also prepared using mutagenic introductiontechnique by a PCR method. Each of the versions “g” and “h” was designedso as to replace the 36-position amino acid, histidine, (amino acidnumber 36 according to the definition by Kabat) with tyrosine in theversions “a” and “d”, respectively. The PCR reaction was conducted withmutagenic primer MBC1LGP9R (SEQ ID NO: 0.39) and M13 Primer RV usingplasmid hMBC1Laλ/pUC19 as a template. The PCR product was subjected toan additional PCR reaction using M13 Primer M4 as a primer and plasmidhMBC1Laλ/pUC19 as a template. The DNA fragment obtained was digestedwith HindIII and BlnI and then subcloned into plasmid Cλ/pUC19 which hadbeen prepared by digesting the plasmid with HindIII and BlnI. Using thisplasmid as a template, a PCR reaction was conducted using primersMBC1LGP13R (SEQ ID NO: 40) and MBC1LVS1. The PCR fragment obtained wasdigested with ApaI and HindIII and then introduced into each of plasmidshMBC1Laλ/pUC19 and hMBC1Ldλ/pUC19 which had been prepared by digestingboth plasmids with ApaI and HindIII. The plasmids obtained weredetermined of their DNA sequences. Plasmids which were confirmed tocontain a correct sequence were designated “hMBC1Lgλ/pUC19” and“hMBC1Lhλ/pUC19”, respectively. Each of these plasmids was digested withEcoRI to obtain a sequence containing a sequence coding for thehumanized L chain. The sequence was introduced into the EcoRI site ofplasmid pCOS1 so that the initiation codon for the humanized L chain waslocated downstream from the EF1α promoter. The plasmids thus obtainedwere respectively designated “hMBC1Lgλ/pCOS1” and “hMBC1Lhλ/pCOS1”.

Versions “i”, “j”, “k”, “l”, “m”, “n” and “o” were also prepared usingmutagenic introduction technique by a PCR method. The PCR reaction wasconducted using a mutagenic primer MBC1LGP14S (SEQ ID NO: 41) and primerV1RV (λ) (SEQ ID NO: 43) using plasmid hMBC1Laλ/pUC19 as a template. Theresultant DNA fragment was digested with ApaI and BlnI and thensubcloned into plasmid hMBC1Lgλ/pUC19 which had been prepared bydigesting the plasmid with ApaI and BlnI. The plasmid obtained wasdetermined of its base sequence, and the clone into which the mutationcorresponding to each of the versions was introduced, was selected. Theplasmid thus obtained was designated “hMBC1Lxλ/pUC19 (x=i, j, k, l, m, nor o)”. This plasmid was digested with EcoRI to obtain a sequencecontaining a sequence coding for the humanized L chain. The sequence wasintroduced into the EcoRI site of plasmid pCOS1 so that the initiationcodon for the humanized L chain was located downstream from the EF1αpromoter. The plasmid thus obtained was designated “hMBC1Lxλ/pCOS1”(x=i, j, k, l, m, n or o). The DNA sequences (including thecorresponding amino acid sequences) of the versions “j”, “l”, “m” and“o” are shown in SEQ ID NOs: 67, 68, 69 and 70, respectively. The aminoacid sequences of these versions are shown in SEQ ID Nos: 48, 49, 50 and51, respectively.

Versions “p”, “q”, “r”, “s” and “t” are modified form of the versions“i”, “j”, “m”, “l” and “o”, respectively, in which the 87-position aminoacid, tyrosine, is replaced with isoleucine. These versions wereprepared by using the Aor51MI restriction site of FR3 for replacement ofthe version “h” with the version “i”, “j”, “m”, “l” or “o” in thefollowing manner. From expression plasmid hMBC1Lxλ/pCOS1 (x=i, j, m, lor o), an Aor51HI restriction fragment (514 bp) containing CDR3, aportion of FR3 and entire FR4 were deleted. To the deleted portion ofthe expression plasmid was ligated an Aor51HI restriction fragment (514bp) containing CDR3 and a portion of FR3 and entire FR4 so that the91-position amino acid, tyrosine, (the amino acid number 87 according tothe definition by Kabat) is replaced with isoleucine. The resultantplasmids were determined of their DNA sequence and the clone of each ofthe versions “i”, “j”, “m”, “l” and “o” in which 91-position amino acid,tyrosine, (the amino acid number 87 according to the definition byKabat) was replaced with isoleucine was selected. The versionscorresponding to the versions “i”, “j”, “m”, “l” and “o” were designatedversions “p”, “q”, “s”, “r”, and “t”, respectively, and the plasmids forthese versions were designated “hMBC1Lxλ/pCOS1 (x=p, q, s, r or t). TheDNA sequences (including the corresponding amino acids) of the versions“q”, “r”, “s” and “t” are shown in SEQ ID Nos: 71, 72, 73 and 74,respectively. The amino acid sequences of these versions are shown inSEQ ID Nos: 52, 53, 54 and 55, respectively.

Plasmid hMBC1Lqλ/pCOS1 was digested with HindIII and EcoRI and thensubcloned into plasmid pUC19 by digesting the plasmid with HindIII andEcoRI. The plasmid thus obtained was designated “hMBC1Lqλ/pUC19.

The position of the replaced amino acids in each version of thehumanized L chain is shown in Table 3 below.

TABLE 3 Position of replaced amino acid in sequence lists (amino acidnumber according to the definition by Kabat) Version 36 43 45 47 49 8087 a b P D c P d I e P D I f P I g Y h Y I i Y K j Y K D k Y K V l Y K VD m Y D n Y V o Y V D p Y K I q Y K D I r Y D I s Y K V D I t Y V D I

In Table 3 above, capital letters represent the following amino acids:Y: tyrosine; P: proline; K: lysine, V: valine; D: aspartic acid; and I:isoleucine.

E. coli strain containing plasmid hMBC1HcDNA/pUC19 and E. coli straincontaining plasmid hMBC1Lqλ/pUC19 were designated “Escherichia coliJM109 (hMBC1HcDNA/pUC19)” and “Escherichia coli JM109 (hMBC1Lqλ/pUC19)”,respectively, which have been deposited under the terms of BudapestTreaty at the National Institute of Bioscience and Human-Technology,Agency of Industrial Science and Technology, Japan, (1-3, Higashi1-chome, Tsukuba-shi, Ibaragi-ken, Japan) on Aug. 15, 1996 under theaccession No. FERM BP-5629 for Escherichia coli JM109 (hMBC1HcDNA/pUC19)and FERM BP-5630 for Escherichia coli JM109 (hMBC1Lqλ/pUC19).

(5) Transfection into COS-7 Cell

For determining the antigen-binding activity and the neutralizingactivity of the hybrid antibody and the humanized #23-57-137-1 antibody,the above-mentioned expression plasmids were expressed transiently inCOS-7 cells. For the transient expression of the L chain hybridantibody, each of the following combinations of plasmids wasco-transfected into a COS-7 cell by electroporation using Gene Pulser(Bio Rad): hMBC1HcDNA/pCOS1 and h/mMBC1L(λ)/neo; hMBC1HcDNA/pCOS1 andm/hMBC1Laλ/neo; hMBC1HcDNA/pCOS1 and m/hMBC1Ldλ/neo; hMBC1HcDNA/pCOS1and hmmMBC1L(λ)/neo; and hMBC1HcDNA/pCOS1 and mhmMBC1L(λ)/neo. That is,into 0.8 ml of a cell suspension in which COS-7 cells were suspended inPBS(−) in a concentration of 1×10⁷ cells/ml, 10 μg of each of theplasmid DNAs was added. The resultant solution was applied with pulsesat an electrostatic capacity of 1,500V and 25 μF. After 10 min. ofrecovery period at room temperature, the cells treated byelectroporation were suspended in a DMEM medium supplemented with 2%Ultra Low IgG fetal calf serum (GIBCO) and then cultured using a 10 cmculture dish in a CO₂ incubator. After culturing for 72 hours, a culturesupernatant was collected and centrifuged to remove cell debris. Theresultant was provided as a sample for the ELISA assay.

For the transient expression of the humanized #23-57-137-1 antibody, theplasmid combination of either hMBC1HcDNA/pCOS1 or hMBC1Lxλ/pCOS1 (x=a−t)was transfected into a COS-7 cell using Gene Pulser (Bio Rad) in thesame manner as described for the hybrid antibody above. The culturesupernatant obtained was provided as a sample for the ELISA assay.

Here, the purification of the hybrid antibody or the humanized antibodyfrom the culture supernatant of COS-7 cell was conducted using AffiGelProtein A MAPSII Kit (Bio Rad) in accordance with an instructionincluded in the kit.

(6) ELISA Assay

(i) Determination of Antibody Concentration

An ELISA plate for determining antibody concentration was prepared asfollows. Each of the wells of a 96-well plate for ELISA (Maxisorp, NUNC)was coated with 100 μl of a coating buffer (0.1 M NaHCO₃, 0.02% NaN₃)supplemented with 1 μg/ml of goat anti-human IgG antibody (TAGO) andthen blocked with 200 μl of a dilution buffer (50 mM Tris-HCl, 1 mMMgCl₂, 0.1 M NaCl, 0.05% Tween20, 0.02% NaN₃, 1% bovine serum albumin(BSA); pH 7.2). Into each of the wells was added a culture supernatantof the COS cells in which the hybrid antibody or the humanized antibodywas expressed or a solution of the purified hybrid antibody or humanizedantibody in stepwise dilution. After incubating at room temperature for1 hour and washing with PBS-Tween20, 100 μl of alkalinephosphatase-conjugated goat anti-human IgG antibody (TAGO) was added toeach of the wells. After incubating at room temperature for 1 hour andwashing with PBS-Tween20, 1 mg/ml of a substrate solution (“Sigma104”,p-nitrophenylphosphoric acid, SIGMA) was added to each of the wells. Thesolution was measured for absorbance at 405 nm using Microplate Reader(Bio Rad). As the standard for this determination of antibodyconcentration, Hu IgG1λ Purified (The Binding Site) was used.

(ii) Determination of Antigen Binding Ability

An ELISA plate for determining antigen binding ability was prepared asfollows. Each of the wells of a 96-well plate for ELISA (Maxisorp, NUNC)was coated with 100 μl of a coating buffer supplemented with 1 μg/ml ofhuman PTHrP (1-34) and then blocked with 200 μl of a dilution buffer.Thereafter, into each of the wells, was added a culture supernatant ofthe COS-7 cells in which the hybrid antibody or humanized antibody wasexpressed or a solution of the purified hybrid antibody or the purifiedhumanized antibody in stepwise dilution. After incubating at roomtemperature and washing with PBS-Tween20, 100 μl of alkalinephosphatase-conjugated goat anti-human IgG antibody (TAGO) was added toeach of the wells. After incubating at room temperature and washing withPBS-Tween20, 1 mg/ml of a substrate solution (“Sigma 104”,p-nitrophenylphosphoric acid, SIGMA) was added to each of the wells. Thesolution was measured for absorbance at 405 nm using Microplate Reader(Bio Rad).

(7) Confirmation of Activities

(i) Evaluation of Humanized H Chain

It was found that an antibody comprising the humanized H chain version“a” and the chimeric L chain exhibited the same level of PTHrP-bindingactivity as that of the chimeric antibody (see FIG. 5). This resultsuggests that the humanization of the H chain V region is satisfactorilyachieved by the version “a”. Therefore, the humanized H chain version“a” was provided as a humanized antibody H chain in the followingexperiments.

(ii) Activity of Hybrid Antibody

(ii-a) FR1,2/FR3,4 Hybrid Antibody

When the L chain was h/mMBC1Ld(λ), the antibody showed no antigenbinding activity. However, when the L chain of the hybrid antibody waseither m/hMBC1Laλ or m/hMBC1Ldλ, the antibody showed the same level ofantigen binding activity as that of the chimeric #23-57-137-1 antibody(FIG. 6). These results suggest that FR3 and FR4 are suitable for ahumanized antibody but there exist amino acid residue(s) that need to bereplaced in FR1 and FR2.

(ii-b) FR1/FR2 Hybrid Antibody

When the L chain of the hybrid antibody was mhmMBC1L (λ), the antibodyshowed no antigen binding activity. However, when the L chain of thehybrid antibody was hmmMBC1L(λ), the antibody showed the same level ofantigen binding activity as that of the chimeric #23-57-137-1 antibody(FIG. 7). These results suggest that FR1 is suitable for a humanizedantibody but there exist amino acid residue(s) that need to be replacedin FR2.

(iii) Activity of Humanized Antibody

The humanized antibody in which each of the versions “a” to “t” was usedas the L chain was determined of its antigen-binding activity. As aresult, it was found that the humanized antibodies having the L chainversions “j”, “l” “m”, “o”, “q”, “r”, “s” and “t” exhibited the samelevel of PTHrP-binding activity as that of the chimeric antibody (FIGS.8 to 11).

(8) Establishment of CHO Stable Production Cell Line

For establishing a stable transformant for humanized antibody, theabove-mentioned expression plasmids were introduced into a CHO cell(DXB11).

The establishment of a stable transformant of the humanized antibody wasconducted using each of the following combinations of plasmid as anexpression vector for CHO cells; hMBC1HcDNA/pCHO1 and hMBC1Lmλ/pCOS1;hMBC1HcDNA/pCHO1 and hMBC1Lqλ/pCOS1; and hMBC1HcDNA/pCHO1 andhMBC1Lrλ/pCOS1. The plasmids were co-transfected into a CHO cell byelectroporation using Gene Pulser (Bio Rad). Subsequently, each of theexpression vectors was cleaved with restriction enzyme PvuI to obtain alenear DNA. The resultant DNA was extracted with phenol and chloroformand then precipitated with ethanol. The DNAs thus prepared wererespectively subjected to electroporation as follows. That is, 10 μg ofeach of the plasmid DNAs was added to 0.8 ml of a cell suspensioncontaining CHO cells in PBS(−) in a concentration of 1×10⁷ cells/ml. Theresultant mixture was applied with pulses at an electrostatic capacityof 1,500V and 25 μF. After 10 min. of recovery period at roomtemperature, the cells thus treated were suspended in a MEM-α medium(GIBCO) supplemented with 10% fetal calf serum (GIBCO) and then culturedin a CO₂ incubator using 96-well plates (Falcon). On the day afterstarting the cultivation, the medium was replaced by a MEM-α selectivemedium supplemented with 10% fetal calf serum (GIBCO) and 500 mg/ml ofGENETICIN (G418Sulfate; GIBCO) but containing no ribonucleoside ordeoxyribonucleoside. From the culture medium, cells into which theantibody gene was introduced were selected. After replacing the culturemedium by a fresh one, before and after two weeks of cultivation, thecells were observed microscopically. When a satisfactory cell growth wasobserved, the cells were determined for the amount of antibodiesproduced by an ELISA assay conventionally used for determining antibodyconcentration as described above. Among the cells, those which produceda larger amount of antibodies were selectively collected.

The scale up of the culture of the stable transformant for theantibodies thus established was conducted in a roller bottle using aMEM-α medium supplemented with 2% Ultra Low IgG fetal calf serum withoutribonucleoside or deoxyribonucleoside. On each of day 3 and day 4 afterthe cultivation, the culture supernatant was collected and filteredusing a 0.2 μm filter having (Millipore) to remove cell debristherefrom. The purification of the humanized antibodies from the culturesupernatant of the CHO cells was conducted using POROS Protein A Column(PerSeptive Biosystems) on ConSep LC100 (Millipore) in accordance withan instruction included. The humanized antibodies were provided as asample for the determination of neutralizing activity and examination ofpharmacological efficacy on hypercalcemic model animals. Theconcentration and the antigen-binding activity of the purified humanizedantibodies were determined by the ELISA system as mentioned above.

Example 4 Determination of Neutralizing Activity

The determination of neutralizing activity of the mouse antibody, thechimeric antibody and the humanized antibody was conducted using ratmyeloma cell line ROS17/2.8-5 cells. The ROS17/2.8-5 cells were culturedin Ham'S F-12 medium (GIBCO) supplemented with 10% fetal calf serum(GIBCO) using a CO₂ incubator. The ROS17/2.8-5 cells were inoculated ineach of the wells of a 96-well plate in a concentration of 10⁴ cells/100μl/well and cultured for 1 day. The culture medium was replaced withHam'S F-12 medium (GIBCO) supplemented with 4 mM Hydrocortisone and 10%fetal calf serum. After culturing for three to four days, the culturedcells were washed with 260 μl of Ham'S F-12 medium (GIBCO), and then 80μl of Ham's F-12 medium supplemented with 1 mM isobutyl-1-methylxanthine (IBMX, SIGMA), 10% fetal calf serum and 10 mM HEPES was addedthereto. The resultant mixture was incubated at 37° C. for 30 min.

The mouse antibody, the chimeric antibody and the humanized antibody tobe tested for neutralizing activity were previously diluted stepwise inthe following groups: [10 μg/ml, 3.3 μg/ml, 1.1 μg/ml and 0.37 μg/ml],[10 μg/ml, 2 μg/ml, 0.5 μg/ml and 0.01 μg/ml] and [10 μg/ml, 5 μg/ml,1.25 μg/ml, 0.63 μg/ml and 0.31 μg/ml]. Each of the diluted antibodysample solution was mixed with an equivalent amount of 4 ng/ml of PTHrP(1-34). Eighty μl of the resultant mixture solution was added into eachwell. The final concentration of each antibody became a quarter of theconcentration of the above-mentioned antibody, and therefore theconcentration of PTHrP (1-34) became 1 ng/ml. Ten minutes after thetreatment at room temperature, the culture supernatant was removed andthe residue was washed with PBS three times. From the resultant, cAMP inthe cells was extracted with 10 μl of a 0.3% HCl-95% ethanol and thenevaporated with a water jet aspirator to remove the HCl-ethanol. Theresidue was dissolved in 120 μl of EIA buffer attached to cAMP EIA Kit(CAYMAN CHEMICAL'S) to extract the cAMP therefrom. The cAMP level wasdetermined using cAMP EIA Kit (CAYMAN CHEMICAL'S) in accordance with aninstruction included within. As a result, it was found that, among thehumanized antibodies having L chain versions showing the same level ofantigen-binding activity as that of the chimeric antibody, those havingL chain versions “q”, “r”, “s” and “t” in which the 91-position tyrosinewas replaced with isoleucine exhibited the closest neutralizing activityto that of the chimeric antibody, and especially those having a L chainversion “q” exhibited the strongest neutralizing activity (FIGS. 12 to14).

Example 5 Examination of Pharmacological Efficacy on Hypercalcemic ModelAnimals (1)

Using a hypercalcemic model animal (a human tumor transplanted nudemouse), a chimeric antibody and humanized antibodies individually havingL chain versions “m”, “r” and “q” against PTHrP were examined for theirtherapeutic efficacy on hypercalcemia.

As a hypercalcemic model animal, was used a nude mouse which had beentransplanted with human pancreatic cancer PAN-7 [purchased from theCentral Institute for Experimental Animals]. It has been known that anude mouse which has been transplanted with human pancreatic cancerPAN-7 exhibits an increased calcium concentration in blood as increasingthe tumor volume and develops hypercalcemia which is associated with,for example, decrease in body weight and spontaneous activity. In thisexample, therapeutical effect of the chimeric antibody and the humanizedantibody of the invention on hypercalcemia induced by the humanpancreatic cancer PAN-7 was examined by the measurement of body weightand calcium concentration in blood of the test animal.

The passage of the human pancreatic cancer PAN-7 was conducted usingBALB/c-nu/nu nude mice (Nippon Charles River) in vivo. For theevaluation of pharmacological efficacy, 5-weeks-old male BALB/c-nu/nunude mice (Nippon Charles River) were purchased and then acclimatizedthem for 1 week, and the mice of 6-weeks-old thus prepared were used forthe evaluation. The hupercalcemic model mice were prepared and dividedinto groups in the following manner. The human pancreatic cancer PAN-7passed was excised and then finely cut into 3 mm cube of blocks. Theresultant tumor blocks were subcutaneously transplanted under the skinflap of the mice at one piece per mouse. Two or three weeks after thetransplantation, when it was confirmed that the tumor volume in each ofthe mice became satisfactorily large, the mice were divided into groupsso that tumor volume, calcium concentration in blood and body weights ofthe mice of the individual groups were averaged, and the mice were usedas the hupercalcemic model animals.

The examination of therapeutic efficacy on hypercalcemia was conductedas follows. A single dose of the chimeric antibody or the humanizedantibody having a L chain version “m” or “r” against PTHrP wasadministered to each of the above-mentioned hypercalcemic model mice viatail vein in a dose amount of 10 or 30 μg per mouse. A single dose ofthe humanized antibody having a L chain version “q” was administered toeach of the above-mentioned hypercalcemic model mice via tail vein in adose amount of 20 or 60 μg per mouse. On day 1, day 4, day 7 and day 11after the administration, each of the mice was measured for the calciumconcentration in blood and measured for the body weigh to evaluate thepharmacological efficacy of the antibodies. The tumor volume wasdetermined by measuring the major diameter (a mm) and the minor diameter(b mm) of the tumor and calculating using the both measured valuesaccording to Galant's equation [ab²/2]. The calcium concentration inblood was determined as ionized calcium concentration in whole blood bydrawing blood from each of the mice via the orbit using a hematocrittube and applying the blood to 643 Automatic Ca++/pH Analyzer(CIBA-CORNING).

As a result, it was found that the administration of the chimericantibody and the humanized antibodies each having the L chain versions“m”, “r” and “q” leads to a rapid improvement in change of body weightand calcium concentration in blood and a retention of improvement for aprolonged period of time for a subject. This result showed that thechimeric antibody and the humanized antibodies of the present inventionare useful for treating malignant tumor-associated hypercalcemia (seeFIGS. 15 and 16).

Example 6 Examination of Pharmacological Efficacy on Hypercalcemia ModelAnimals (2)

Using a hypercalcemia model animal (a human tumor transplanted nudemouse), a chimeric antibody and a humanized antibody having L chainversion “q” against PTHrP were examined for their therapeutic efficacyon hypercalcemia as follows.

The examination for the therapeutic efficacy on hypercalcemia wasconducted as follows. A single dose of the chimeric antibody or thehumanized antibody having a L chain version “q” against PTHrP wasadministered to each of the above-mentioned hypercalcemia model mice viatail vein in a dose amount of 10 or 30 μg per mouse. On day 1, day 3,day 7 and day 11 after the administration, each of the mice wasdetermined for the calcium concentration in blood and measured for thebody weigh to evaluate the pharmacological efficacy of the antibodies.The calcium concentration in blood was determined as ionized calciumconcentration in whole blood by drawing blood from each of the mice viathe orbit using a hematocrit tube and applying the blood to 643Automatic Ca⁺⁺/pH Analyzer (CIBA-CORNING).

As a result, in the hypercalcemia model animal carrying human pancreaticcancer PAN-7, the administration of the chimeric antibody and thehumanized antibody having the L chain version “q” leads to a rapidimprovement with respect to body weight and calcium concentration inblood and to a retention of improvement for a prolonged time period fora subject. This result suggests that the chimeric antibody and thehumanized antibody of the present invention are useful agent fortreating malignant tumor-associated hypercalcemia (see FIG. 17).

Example 7 Examination of Pharmacological Efficacy on Hypercalcemia ModelAnimals (3)

Using a hypercalcemia model animal (a human lung cancer LC-6transplanted nude mouse), a chimeric antibody and a humanized antibodyhaving L chain version “q” against PTHrP were examined for theirtherapeutic efficacy on hypercalcemia.

In this experiment, as the hypercalcemia model animal, a nude mouse intowhich human lung cancer LC-6 (purchased from the Central Institute forExperimental Animals) was transplanted was used. It has been known thata nude mouse into which human lung cancer LC-6 is transplanted tends toshow an increased calcium concentration in blood with increased tumorvolume and develops hypercalcemia associated with decrease in bodyweight and spontaneous activity.

In this example, therapeutic efficacy of the chimeric antibody and thehumanized antibody of the invention on hypercalcemia induced by thehuman lung cancer LC-6 was examined by the measurement of body weightand calcium concentration in blood of the test animal.

The passage of the human lung cancer strain LC-6 was conducted usingBALB/c-nu/nu nude mice (Nippon Charles River) in vivo. For theevaluation of pharmacological efficacy, 5-weeks-old male BALB/c-nu/nunude mice (Nippon Charles River) were purchased and then acclimatizedthem for 1 week, and the mice of 6-weeks-old were used.

The hypercalcemia model mice were prepared and divided into groups inthe following manner. The human lung cancer LC-6 passaged was excisedand then finely cut into 3 mm cube of blocks. The resultant tumor blockswere subcutaneously transplanted under the skin flap of the mice at onepiece per mouse. Two or three weeks after the transplantation, when itwas confirmed that the tumor volume in each of the mice had becomesatisfactorily large, the mice were divided into groups so that tumorvolume, calcium concentration in blood and body weight of the mice ofthe individual groups were averaged, and the mice were used as thehypercalcemia model animals.

The examination of therapeutic efficacy on hypercalcemia was conductedas follows. A single dose of the chimeric antibody or the humanizedantibody having a L chain version “q” against PTHrP was administered toeach of the above-mentioned hypercalcemia model mice via tail vein in adose amount of 10 or 30 μg per mouse. On day 1, day 3, day 6 and day 10after the administration, each of the mice was measured for the calciumconcentration in blood and measured for the body weigh to evaluate thepharmacological efficacy of the antibodies. The calcium concentration inblood was determined as ionized calcium concentration in whole blood bydrawing blood from each of the mice via the orbit using a hematocrittube and applying the blood to 643 Automatic Ca⁺⁺/pH Analyzer(CIBA-CORNING).

As a result, it was found that in the hypercalcemia model animalcarrying human lung cancer LC-6, the administration of the chimericantibody and the humanized antibody having the L chain version “q” leadsto a rapid improvement with respect to body weight and calciumconcentration in blood and to a retention of improvement for a prolongedtime period for a subject. This result suggests that the chimericantibody and the humanized antibody of the present invention are usefulagent for treating malignant tumor-associating hypercalcemia (see FIG.18).

Example 8 Kinetic Analysis of Interaction Between PTHrP and anti-PTHrPAntibody Using BIACORE

In this experiment, kinetic analysis of the antigen-antibody interactionusing BIACORE was conducted. PTHrP(1-34+Cys) was used as an antigen andadsorbed onto the sensor tip specifically for C-terminals. Purifiedantibodies of various concentrations were used as an analyte. From thesensorgram obtained, kinetics parameters (binding rate constant “kass”and dissociation rate constant “kdiss”) were calculated. With respect tothe kinetic analysis, literature “Kinetic analysis of monoclonalanbtibody-antigen interactions with a new biosensor based analyticalsystem”, Karlsson, R. et al., (1991), J. Immunol. Methods 145, p.229-240, was used for reference.

(1) Immobilization of PTHrP (1-34+C) Onto the Sensor Tip

PTHrP (1-34+C) was adsorbed onto sensor tip CM5 (Pharmacia).

As a running buffer, HBS (10 mM HEPES, pH 7.4; 0.15 M NaCl; 3.4 mM EDTA;0.005% Surfactant P20) at a flow rate of 5 μl/min. was employed. Thecalboxyl groups of calboxymethyldextran on the sensor tip CM5 wereactivated by an injection of 100 μl of 0.05M N-hydroxysuccinimide(NHS)/0.2M N-ethyl-N′-(3-dimethylaminopropyl)carbodiimide hydrochloride(EDC) and an injection of 100 μl of 80 mM2-(2-pyridinyldithio)ethanamine (PDEA)/0.1M borate buffer (pH 8.5), andan additional injection of 10 μl of 5 μg/ml PTHrP (1-34+C)/10 mM sodiumacetate buffer (pH 5.0) to adsorbe onto the C-terminals of PTHrP(1-34+C) specifically for Cys residues. Subsequently, an injection of100 μl of 50 mM (L)-cystein/1M NaCl/0.1M sodium formate buffer (pH 4.3)was conducted to block excessively activated groups. Subsequently, aninjection of 10 μl of 0.1M glycine-HCl buffer (pH2.5) and 10 μl of 10 mMHCl was conducted to wash the substances having non-covalent bonding.The amount of the PTHrP (1-34+C) thus immunolized was 226.4 RU(resonance units) (FIG. 19).

(2) Interaction Between Immunolized PTHrP (1-34+C) and Purified MouseAnti-PTHrP Antibody

As a running buffer, HBS at a flow rate of 20 μl/min. was used. Theantibody producing hybridomas were injected into the abdominal cavity ofa Balb/c mouse and after a couple of weeks, the ascites were collectedand applied on protein A column to purify antibodies. The purified#23-57-137-1 antibody was designated “MBC” and the purified 3F5 antibodywas designated “3F5”. These antibodies were diluted with HBS in a seriesof concentrations of 1.25, 2.5, 5, 10 and 20 μg/ml.

In the analysis, 40 μl of the antibody solution was injected for 2 min.to give a binding phase, and then HBS was injected for 2 min. to give adissociation phase. After the dissociation was completed, 10 μl of 10 mMHCl was injected to recover the sensor tip. The analysis was conductedby using this binding-dissociation-recovering as one cycle and injectingvarious antibody solutions to obtain a sensorgram.

(3) Interaction Between Immobilized PTHrP (1-34+C) and PurifiedHumanized Anti-PTHrP Antibody

As a running buffer, HBS at a flow rate of 20 μl/min. was used. Theantibody was produced by CHO cells and purified using protein A column.The purified chimeric antibody was designated “chMBC”, and the purifiedhumanized antibodies of versions m and q were designated “hMBCm” and“hMBCq”, respectively, These antibodies were diluted with HBS in aseries of concentrations of 1.25, 2.5, 5, 10 and 20 μg/ml.

In the analysis, 40 μl of the antibody solution was injected for 2 min.to give a binding phase, and then HBS was injected for 2 min. to give adissociation phase. After the dissociation was completed, 10 μl of 10 mMHCl was injected to recover the sensor tip. The analysis was conductedby using a binding-dissociation-recovering as one cycle and by injectingvarious antibody solutions to obtain a sensorgram.

(4) Kinetic Analysis of the Interaction

The date file of interest was read and a comparison of the reactionpatterns was conducted by overlaying the reaction regions of interest(FIGS. 20-24). In each of FIGS. 20-24, lines sequentially indicate fromthe top the data for the antibody concentrations 1.25, 2.5, 5, 10 and 20μg/ml. Further, kinetic analysis of the interaction was conducted usingan analysis software specifically designed for BIACORE “BIAevaluation2.1” (Pharmacia) which is capable of calculating the kinetics parameters(binding rate constant “kass” and dissociation rate constant “kdiss”) bycurve cutting (Tables 4 and 5).

TABLE 4 Kinetics parameters of MBC and 3F5 MBC 3F5 Kdiss [l/s] 7.38 ×10⁻⁵ 1.22 × 10⁻² Kass [l/Ms] 7.23 × 10⁵ 6.55 × 10⁵ KD [M] 1.02 × 10⁻¹⁰1.86 × 10⁻⁸

TABLE 5 Kinetics parameters of chimeric and humanized antibodies chH-chλhMBCm hMBCq Kdiss [l/s] (×10⁻⁴) 1.66 3.16 2.32 Kass [l/Ms] (×10⁶) 1.240.883 1.03 KD [M] (×10⁻¹⁰) 1.34 3.58 2.25

In this experiment, for determining the binding rate constant, analysismodel type 4 (BIAevaluation 2.1 Software Handbook, A1-A5) was used.

Example 9

Suppression of Excretion of Phosphorus in a Model of MalignantTumor-Associated Hypercalcemia

Malignant tumor-associated hypercalcemia (HHM) is a disease caused bythe presence of PTHrP and it has been known that PTHrP accelerates boneresorption and calcium resorption in kidney and riniferous tubule,resulting in the development of hypercalcemia. On the other hand, withrespect to phosphorus, PTHrP suppress the resorption of phosphorus inthe kidney and riniferous tubule, resulting in the development ofeliminant action, and therefore clinical HHM patients often develophypophosphatemia. Here, the effect of humanized anti-PTHrP antibody onexcretion of phosphorus in the kidney was examined using malignanttumor-associated hypercalcemia model rats.

As a model animal, a nude rat into which human lung cancer LC-6(purchased from the Central Institute for Experimental Animals) wastransplanted was used. It has been known that a nude rat into whichhuman lung cancer LC-6 was subcutaneously transplanted tends to show anincreased calcium concentration in blood was the increase of the tumorvolume and, as a result, the rat develops hypercalcemia which isassociated with, for example, decrease in body weight and spontaneousactivity. Using this model animal, the effect of the humanizedanti-PTHrP antibody of the invention on phosphate excretion in thekidney was examined by a renal clearance method based on thebelow-mentioned fractional excretion of phosphate.

The passage of the human lung cancer LC-6 was conducted usingBALB/c-nu/nu nude mice (Nippon Kurea) in vivo. For the evaluation ofpharmacological efficacy, 5-weeks-old male F344N/Jcl-rnu nude rats(Nippon Kurea) were purchased and then acclimatized them for 1 week, andthe rats of 6-weeks-old were used.

The malignant tumor-associated hupercalcemic model animals were preparedas follows. The human lung cancer LC-6 tumor passaged was excised andthen finely cut into 3 mm cube of blocks. The resultant tumor blockswere subcutaneously transplanted under the skin flap of the rats at onepiece per rat. About thirty days after the transplantation, when it wasconfirmed that the tumor volume in each of the rats becamesatisfactorily large (3000 mm³), the rats to be provided as themalignant tumor-associated hypercalcemia model animals were selectedbased on calcium concentration in blood and body weight.

The examination of phosphate excretion by a renal clearance method wasconducted in the following manner.

(1) Renal Clearance Method

A malignant tumor-associated hypercalcemia model animal was anesthetizedwith pentobarbital (Nembutal, Dainippon Pharmaceutical Co., Ltd.), fixedsupinely onto a incubation mat maintained at 37° C., and inserted acannula (a polyethylene tube, PE50, Nippon Beckton Dickinson) to itsbladder to collect urine. Subsequently, the model animal was inserted acannula for infusion (a polyethylene tube, PE10, Nippon BecktonDickinson) to its femoral vein, and then an infusion solution (0.7%inulin, 5% mannitol, 0.2% pentobarbital and 0.9% sodium chloride) wasintroduced into the model animal through the cannula at a flow rate of 2ml/hr using an infusion pump (Terufusion syringe pump; STC-525; TERUMO)to infuse the model animal. After equilibrating for 50 min., urine wascollected through the cannula for five times at 20 min. intervals (i.e.,from period-1 to period-5) to give urine samples. At the intermediatepoint of time during each urine collection procedure, approximately 0.25ml of blood samples from the right cervical vein of the model animalwere collected using a heparin-treated injection syringe.

(2) Administration of Antibody

During the above-mentioned clearance test, at the point of time wherethe collection of urine of period-2 was just started, a humanizedanti-PTHrP antibody was administered intravenously to the animal in adose amount of 1 mg/ml/kg.

(3) Determination of Concentration of Inulin and Phosphorus in Urine andBlood

The urine samples obtained at period-1 to period-5 were measured fortheir volume and then determined for the inulin and phosphorusconcentrations thereof. The blood samples also obtained above weresubjected to cooling centrifugation to obtain a plasma sample, which wasused for determining the inulin and phosphorus concentration. Thedetermination of inulin was conducted by Anthrone-sulfate method (Roe,L. et al., J. Biol. Chem. 178, 839-845, 1949), and the determination ofphosphorus was conducted using Hitachi Automatic Analyzer 7170 modelwith a regent for inorganic phosphorus determination, Autosera IP(Daiichi Pure Chemicals) in accordance with a manual (Physke-Sabarohmethod).

(4) Calculation of Inulin Clearance, Phosphorus Clearance and FractionalExcretion of Phosphorus.

Inulin clearance (Cin), phosphorus clearance (Cp) and fractionalexcretion of phosphorus (FEp) were calculated accordng to the followingequations.

Calculation of Inulin Clearance (Cin):Cin=Uin V/PinWherein Cin represents inulin clearance (ml/kg/min); Uin represents theconcentration of inulin in urine (mg/ml); V represents the amount ofurine per unit time (ml/kg/min); and Pin represents the concentration ofinulin in blood (mg/ml).Calculation of Phosphorus Clearance (Cp):Cp=Up V/PpWherein Cp represents phosphorus clearance (ml/kg/min); Up representsthe concentration of phosphorus in urine (mg/ml); V represents theamount of urine per unit time (ml/kg/min); and Pp represents theconcentration of phosphorus in blood (mg/ml).Calculation of Fractional Excretion of Phosphorus (FEp):FEp=Cp/CinWherein FEp represents fractional excretion of phosphorus; Cinrepresents inulin clearance; and Cp represents phosphorus clearance. Theexamination was conducted using four animals. The results weredetermined as the average value±standard error.

The results of fractional excretion of phosphorus and phosphorusconcentration in blood are shown in FIGS. 25 and 26.

FIG. 25 is a graph illustrating the relationship of fractional excretionof phosphorus (=phosphorus clearance/inulin clearance) vs. periods ofclearance (1 period=20 min.). The humanized anti-PTHrP antibody (1mg/kg) was administered (i.v.) at the time of the starting of period-2.

FIG. 26 is a graph illustrating the relationship of phosphorusconcentration in plasma vs. periods of clearance (1 period=20 min.). Thehumanized anti-PTHrP antibody (1 mg/kg) was administered (i.v.) at thetime of starting of period-2.

From these results, it was found that the fractional excretion ofphosphorus given after administering the antibody (i.e., from period-2and period-5) was obviously suppressed compared with that given beforeadministering the antibody (i.e., period-1). In other words, it wasfound that the administration of the neutralizing antibody to a subjectdeveloping hypophosphatemia, which causes acceleration of excretion ofphosphorus (FEp>0.2) recovered the phosphorus resorption in the subjectto approximately the normal level (fractional resorption ofphosphate=1-FEp>0.8%) and, as a result, trend to normalcy of thephosphorus concentration in blood of the subject was observed. Theseresults suggest the usefulness of the antibodies of the presentinvention as agents treating the accelerated excretion of phosphorus andhypophosphatemia caused by the presence of PTHrP.

Since PTHrP is a substrate causing malignant tumor-associatedhypercalcemia, the possibility of increase in phosphorus excretion anddecrease in high energy organic phosphorus in tissue caused by PTHrP ispredicted. Accordingly, various diseases associated withhypophosphatemia, such as hypophosphatemic rickets and hypophosphatemicvitamine D-resistant rickets, are considered to be mainly caused by theincrease in phosphorus excreted through urine and, therefore, theantibodies of the present invention would also be useful for treatingthese diseases.

Example 10 Improvement of Various Clinical Symptoms of MalignantTumor-Associated Hypercalcemia

It has been known that the malignant tumor-associated hypercalcemia iscaused by the presence of PTHrP which is produced by the tumor and thatPTHrP accelerates bone resorption and calcium resorption in the kidneyand the uriniferous tubule, leading to hypercalcemia. Further, in apatient suffering from hypercalcemia, worsening of clinical symptoms,such as poor performance status, loss of consciousness, systemicmalaise, hydrodipsia, nausea and emesis (anorexia) are observed. Theeffect of the anti-PTHrP antibody on such clinical symptoms was examinedusing hypercalcemia model animals of human tumor nude mousetransplantation system and human tumor-nude rat transplantation system.

As the hypercalcemia model animal, nude mice and nude rats into whichhuman lung cancer LC-6 (purchased from the Central Institute forExperimental Animals) had been transplanted were used. Nude mice andnude rats into which human lung cancer LC-6 is transplanted tend to showincreased calcium concentration in blood with increase in the tumorvolume, leading hypercalcemia associated with decrease in bodytemperature and body weight.

The improvement effect of mouse anti-PTHrP antibody on general clinicalsymptoms of malignant tumor-associated hypercalcemia was examined usinga human lung cancer LC-6-nude mouse transplantation system and itsresult is shown photographically. The effect of the antibody onimprovement of decrease in spontaneous activity, body temperature andanorexia was examined using a human lung cancer LC-6-nude mousetransplantation system.

1. Improvement of Apparent Clinical Symptoms Associated withHypercalcemia

The passage of the human lung cancer strain LC-6 was conducted usingBALB/c-nu/nu nude mice (Nippon Kurea) in vivo. For the evaluation ofpharmacological efficacy, 5-weeks-old male BALB/c-nu/nu nude mice(Nippon Krea) were purchased and then acclimatized for 1 week, and themice of 6-weeks-old were used.

The hypercalcemia model mice were prepared and divided into groups inthe following manner. The human lung cancer LC-6 passaged was excisedand then finely cut into 3 mm cube of blocks. The resultant tumor blockswere subcutaneously transplanted under the skin flap of the mice at onepiece per mouse. Twenty-seven days after the transplantation, when itwas confirmed that the tumor volume in each of the mice becamesatisfactorily large, the mice were divided into groups so that thetumor volume, the calcium concentration in blood and the body weights ofthe mice of the individual groups were averaged, and the mice wereprovided as the hypercalcemia model animals.

The tumor volume was determined by measuring the major diameter (a mm)and the minor diameter (b mm) of the tumor and calculating using theboth measured values according to Galant's equation [ab²/2].

The calcium concentration in blood was determined as ionized calciumconcentration in whole blood by drawing blood from each of the mice viathe orbit using a hematocrit tube and applying the blood to 643Automatic Ca⁺⁺/pH Analyzer (CIBA-CORNING).

The examination of therapeutic efficacy of the antibody on hypercalcemiawas conducted in the following manner. The mouse antibody against PTHrPwas administered to each of the above-mentioned hypercalcemia modelanimal via the tail vein on day 27, 30, 34 and 37 after transplantingthe tumor in a dose amount of 100 μg per mouse. For preparation ofcontrols, a phosphate buffered-physiological saline was administeredinstead of the antibody in the same manner. On 41 days aftertransplanting the tumor, from each of the antibody-administered groupand the control group, a typical mouse was selected and a picture wastaken thereof along with a normal mouse.

As a result, in the hypercalcemia model animal transplanted with humanlung cancer LC-6, although the antibody-administered mice (shown incenter of each of FIGS. 27 and 28) bore the same level of tumor mass asthe control mouse (shown in the right of each of FIGS. 27 and 28), theyexhibited the same level of appearance as the normal mouse (shown in theleft of FIGS. 27 and 28). This result suggest that the administration ofthe anti-PTHrP antibody exerts an improvement in apparent clinicalsymptoms (FIGS. 27 and 28).

2. Improvement of Spontaneous Activity Decrease Associated withHypercalcemia

The passage of the human lung cancer LC-6 was conducted usingBALB/c-nu/nu nude mice (Nippon Kurea) in vivo. For the evaluation ofphrmacological efficacy, 5-weeks-old male F344/N Jcl-run nude rats(Nippon Krea) were purchased and then acclimatized for 1 week, and therats of 6-weeks-old were used.

The hypercalcemia model animals were prepared in the following manner.The human lung cancer LC-6 passaged was excised and then finely cut into3 mm cube of blocks. The resultant tumor blocks were subcutaneouslytransplanted under the skin flap of the mice at one piece per mouse.About thirty days after the transplantation, when it was confirmed thatthe tumor volume in each of the mice had become satisfactorily large,the mice were divided into groups so that the tumor volume, the calciumconcentration in blood and the body weights of the mice of theindividual groups were averaged, and the mice were provided as thehypercalcemia model animals.

The calcium concentration in blood was determined as ionized calciumconcentration in whole blood by drawing blood from each of the mice viathe orbit using a hematocrit tube and applying the blood to 643Automatic Ca⁺⁺/pH Analyzer (CIBA-CORNING).

(1) Method for Determination of Spontaneous Activity

The determination of spontaneous activity was conducted using ANIMEXactivity meter type SE (FARAD, Electronics, Sweden), which was placed inpredetermined position in the polyethylene cage in which each of themodel animals was individually nurtured (watering and feeding). Thisapparatus was designed to measure the amount of movement of each rat.Using this apparatus, the amount of movement was recorded as the countper a definite time of period. The measurement was conducted for 13hours (from 7:00 p.m. of a certain day to 8:00 a.m. of next day) and theresults were given as count per hour.

(2) Administration of Antibody

The humanized anti-PTHrP antibody was administered each of theabove-prepared rats which developed hypercalcemia via its tail vein as acontrol in a dose amount of 5 mg/0.5 ml/kg. Saline was administered toanother group of the rats in the same manner. The measurement wasconducted with alternation of an antibody-administrated rat and acontrol rat.

The measurement was conducted on day 0 (i.e., the day beforeadministration), 2, 4, 7 and 14 for the antibody-administered rats andon day 1, 3, 5, 8 and 15 for the control rats.

As a result, the control rats showed no change or a decrease inspontaneous activity during the test period, whereas theantibody-administered rats showed an increase in spontaneous activity onand after day 4 of the administration (FIG. 29).

3. Improvement in Body Temperature Decrease Associated withHypercalcemia

The passage of human lung cancer LC-6 and the preparation of themalignant tumor-associated hypercalcemia model animals were conducted inthe same manner as in step 2 above.

(1) Method for Measuring Body Temperature

The measurement of body temperature was conducted using a digitalthermometer by anesthetizing the animal with pentobarbital (Nembutal,Dainippon Pharmaceutical Co., Ltd.) and inserting a temperature sensorinto the rectum thereof.

(2) Administration of Antibody

The humanized anti-PTHrP antibody was administered to each of theabove-mentioned hypercalcemia model rats via the tail vein in a doseamount of 1 mg/ml/kg. For a control, saline was administered to anothermodel rat via the tail vein. Further, a normal rat to which no antibodywas administered was also measured for its body temperature. Themeasurement of body temperature of the rats was conducted on day 0(i.e., the day of the administration), 1, 2 and 3 after theadministration with respect to all of the antibody-administered rats,the control rat and the normal rat.

As a result, the normal rat showed no change in body temperature(34.2-34.4° C.) throughout the test period, whereas the malignanttumor-associated hypercalcemia model rats showed a decrease in bodytemperature by about 2° C. compared with the normal rats. When thehumanized anti-PTHrP antibody was administered to the model rats, it wasconfirmed that the malignant tumor-associated hypercalcemia model ratsrecover their decreased body temperatures to the same level as that ofthe normal rats three days after administration. These results suggeststhat the humanized anti-PTHrP antibody of the present invention iseffective for improving the body temperature decrease of the malignanttumor-associated hypercalcemia model animal (FIG. 30).

4. Improvement in Food Intake Decrease Induced

The passage of the human lung cancer LC-6 and the preparation of thehypercalcemia model animals were conducted in the same manner asdescribed in above section 2. The model animals prepared were dividedinto groups so that the calcium concentration in blood and the bodyweights of the mice of the individual groups were averaged, and the micewere used in the experiments below.

(1) Measurement of Amount of Feed Intake

During the test period, the rats were individually placed into ametabolic cage and nurtured with water and feed. With respect to each ofthe rats, the amount ingested was determined as the amount (g) per 24hours (starting from 9:00 a.m. of a certain day to 9:00 a.m. of the nextday). The determination was conducted by measuring the total weight ofthe feedstock container both at 9:00 a.m. of the day (i.e., tare) and at9:00 a.m. of the next day and calculating the weight differencetherebetween.

(2) Administration of Antibody

The humanized anti-PTHrP antibody was administered to each of thehypercalcemia model rats (HHM rats) described above via its tail vein ina dose amount of 5 mg/0.5 ml/kg. Saline was administered to each ofcontrol group via its tail vein in the same manner. Saline was alsoadministered to each of normal rats via tail vein in the same manner.With respect to all of the antibody-administered rats, the control ratsand the normal rats, the determination of the amount of food intake wasconducted on day 0 (i.e., previous day of the administration to the dayof the administration), day 1 (i.e., period from the day of theadministration to the next day), day 3 (i.e., period from three daysafter the administration to the next day) and day 5 (i.e., period fromfive days after the administration to the next day).

As a result, before administering the antibody, the amount ingested bythe hypercalcemia model rats (5-9 rats) was 8.11 g in average, whereasthat of the normal rats was 12.06 g in average, which demonstrates anobvious decrease in the amount of ingestion by hypercalcemia model rats.When the humanized ante-PTHrP antibody was administered to the modelrats, on and after the day after administering the antibody, althoughalmost no change was observed in the amount of ingestion by the controlrats, the amount of ingested by the antibody-administered rats recoveredto the same level of that in the normal rats. These results suggest thatthe humanized anti-PTHrP antibody of the present invention is effectivein improving the decrease in the amount ingested for the malignanttumor-associated hypercalcemia model (Table 6).

TABLE 6 Effect on ingestion Eating amount of Individual individual (g)Animal No. Administration* day 0 day 1 day 3 day 5 Normal rat 1 Saline13.7 16.7 18.63 18.71 2 Saline 14.27 15.3 19.55 19.39 3 Saline 9.83 15.520.72 19.88 4 Saline 10.42 15.04 20.28 22.03 HHM rat 5 Saline 10.7714.24 12.66 11.82 6 Saline 6.99 8.92 2.59 14.8 HHM rat 7 Anti-PTHrP 7.4617.65 22.52 17.99 antibody 8 Anti-PTHrP 12 12.38 20.94 23.1 antibody 9Anti-PTHrP 3.35 16.65 20.36 21.89 antibody *Administration of saline(Saline): 0.5 ml/kg, via tail vein; and Administration of antibody: 5mg/0.5 ml/kg, via tail vein.

From the above-mentioned results, it was demonstrated that the chimericantibodies and the humanized antibodies of the present invention areuseful as agents for improving the various clinical symptoms ofmalignant tumor-associated hypercalcemia.

5. Improvement of Decrease in Blood pH Induced by Hypercalcemia

The passage of human lung cancer LC-6 and the preparation of themalignant tumor-associated hypercalcemia model animals were conducted inthe same manner as in step 2 above. The model animals were divided intogroups so that the calcium concentration in blood and the body weight ofthe mice of the individual groups were averaged.

(1) Determination of Blood pH

Blood was collected from each test animal using a heparin-treatedinjection syringe by cardiac blood drawing technique and then applyingthe resultant blood sample to 643 Automatic Ca⁺⁺/pH Analyzer(CIBA-CORNING) to determine pH of the blood sample.

(2) Administration of Antibody

The humanized anti-PTHrP antibody was administered to each of theabove-mentioned hypercalcemia model rats (HHM rats) via its tail vein ina dose amount of 5 mg/0.5 ml/kg (n=3). Saline was administered to eachof control group via its tail vein in the same manner (n=2). Withrespect to any of the antibody-administered rats and the control rats,the determination of blood pH was conducted on day 0 (i.e., the day ofadministration), day 1 and day 7. The results are given as average ofthe pH values obtained.

As a result, before administering the antibody, the pH of the bloodobtained from the hypercalcemic model rats was about 7.49 (whereas thatfrom the normal rats was 7.40±0.02), which means that the model ratsobviously had developed metabolic alkalosis. When the humanizedanti-PTHrP antibody of the present invention was administered to themodel rats, although the control rats showed almost no change in bloodpH, the antibody-administered rats showed such an improvement in pHvalues that the pH values recovered to near the pH value of the normalrats seven days after administering the antibody. As one of the clinicalsymptoms of malignant tumor-associated hypercalcemia (HHM), metabolicalkalosis has been reported which is known to be induced by theinhibition of excretion of bicarbonate ion (HCO₃ ⁻) in kidney. Since theadministration of the humanized anti-PTHrP antibody of the presentinvention normalized the blood pH in the hypercalcemia model animals, itis suggested that the antibody can improve the metabolic alkalosis foundin HHM (FIG. 31).

From the results mentioned above, it was demonstrated that the chimericantibodies and the humanized antibodies of the present invention areuseful as agents for improving the clinical symptoms of malignanttumor-associated hypercalcemia.

INDUSTRIAL APPLICABILITY

According to the present invention, a chimeric antibody and a humanizedantibody against PTHrP are provided. These antibodies have a lowantigenicity against human and therefore are useful as agents fortreating hypercalcemia, hypophosphatemia and the like.

1. An isolated DNA encoding the amino acid sequence of a VL chain of ahumanized antibody, said amino acid sequence selected from the groupconsisting of SEQ ID NOs:47-55.
 2. The isolated DNA according to claim1, wherein said DNA is selected from the group consisting of SEQ IDNOs:66-74 and encodes SEQ ID NOs:47-55, respectively.
 3. An isolated DNAencoding the amino acid sequence of a VH chain of a humanized antibody,said amino acid sequence comprising SEQ ID NO:56.
 4. The isolated DNAaccording to claim 3, wherein said DNA SEQ ID NO:58.